fix: UI redesign — horizontal instance rows, proper scaling, readable tag cards

- Backend: add replicas field to InstanceResponse (extracted from values.replicaCount)
- InstanceCard: complete redesign as horizontal row layout
  - Status bar | Name+Chart | Replicas +/- | Action buttons
  - Scale controls show for deployed AND failed statuses (scale to 0)
  - Fix replicas display using new instance.replicas backend field
- InstancesManagementPage: vertical row list + onScale callback to update state
- TagCard: restore proper padding (p-4), min-width, readable button sizes
- ArtifactBrowserPage: reduce grid density (sm:1 md:2 lg:3)
- ModifyModal: simplify to YAML-only editing with current values pre-populated
  - Remove schema-based form generator
  - Keep values-diff as collapsible reference panel

frontend/src/features/artifact/instances/components/ModifyModal.tsx

@@ -7,19 +7,17 @@ import React, { useState, useEffect } from "react";
 import { Settings } from "lucide-react";
 import { parse as parseYaml, stringify as stringifyYaml } from "yaml";
 import type { InstanceResponse, UpdateInstanceRequest } from "@/api";
-import { getValuesSchema, getInstanceValuesDiff } from "@/api";
-import { 
-  Modal, 
-  Button, 
-  FormField, 
-  Input, 
+import { getInstanceValuesDiff } from "@/api";
+import {
+  Modal,
+  Button,
+  FormField,
+  Input,
   Textarea,
   ErrorState,
   LoadingState,
   Badge,
-  SchemaFormGenerator
 } from "@/shared/components";
-import type { JsonSchema } from "@/shared/components/form/SchemaFormGenerator";
 
 interface ModifyModalProps {
   instance: InstanceResponse;
@@ -37,12 +35,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
   const [valuesYaml, setValuesYaml] = useState("");
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
-  
-  // Values Schema support
-  const [loadingSchema, setLoadingSchema] = useState(false);
-  const [valuesSchema, setValuesSchema] = useState<JsonSchema | null>(null);
-  const [inputMethod, setInputMethod] = useState<'form' | 'yaml'>('yaml');
-  const [formValues, setFormValues] = useState<Record<string, any>>({});
 
   // Values Diff support
   const [showDiff, setShowDiff] = useState(false);
@@ -56,15 +48,14 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
   // Initialize with current values
   useEffect(() => {
     setTag(instance.version || "");
-    setDescription(""); // InstanceResponse doesn't have description field
-    
-    // Parse existing values
+    setDescription("");
+
+    // Parse and display existing values as YAML
     if (instance.values) {
       try {
-        const parsedValues = typeof instance.values === 'string' 
-          ? JSON.parse(instance.values) 
+        const parsedValues = typeof instance.values === 'string'
+          ? JSON.parse(instance.values)
           : instance.values;
-        setFormValues(parsedValues);
         setValuesYaml(typeof parsedValues === 'object' ? stringifyYaml(parsedValues) : String(parsedValues));
       } catch (err) {
         console.error('[ModifyModal] Failed to parse existing values:', err);
@@ -72,46 +63,10 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
       }
     }
 
-    // Load values schema
-    loadValuesSchema();
-
-    // Load values diff
+    // Load values diff for reference
     loadValuesDiff();
   }, [instance]);
 
-  const loadValuesSchema = async () => {
-    if (!instance.registryId || !instance.repository || !instance.version) {
-      setValuesSchema(null);
-      setInputMethod('yaml');
-      return;
-    }
-
-    setLoadingSchema(true);
-    try {
-      const schemaResponse = await getValuesSchema({ 
-        registryId: instance.registryId, 
-        repositoryName: instance.repository, 
-        reference: instance.version, 
-      });
-      const normalizedSchema = extractJsonSchema(schemaResponse);
-      setValuesSchema(normalizedSchema);
-      
-      if (normalizedSchema) {
-        setInputMethod('form');
-        console.log(`[ModifyModal] Loaded values schema with ${Object.keys(normalizedSchema.properties ?? {}).length} properties`);
-      } else {
-        setInputMethod('yaml');
-        console.log('[ModifyModal] No values schema available, using YAML input');
-      }
-    } catch (err) {
-      console.error('[ModifyModal] Failed to load values schema:', err);
-      setValuesSchema(null);
-      setInputMethod('yaml');
-    } finally {
-      setLoadingSchema(false);
-    }
-  };
-
   const loadValuesDiff = async () => {
     if (!instance.clusterId || !instance.id) return;
 
@@ -133,9 +88,7 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
 
   const applyDefaults = () => {
     if (!diffData?.defaults) return;
-    const defaultYaml = stringifyYaml(diffData.defaults);
-    setValuesYaml(defaultYaml);
-    setFormValues(diffData.defaults);
+    setValuesYaml(stringifyYaml(diffData.defaults));
   };
 
   /**
@@ -167,11 +120,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
     });
   };
 
-  const handleFormValuesChange = (values: Record<string, any>) => {
-    setFormValues(values);
-    setValuesYaml(stringifyYaml(values));
-  };
-
   const handleSubmit = async (e: React.FormEvent) => {
     e.preventDefault();
     setLoading(true);
@@ -278,59 +226,21 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
           />
         </FormField>
 
-        {/* Values Configuration */}
-        <div className="space-y-3">
-          <div className="flex items-center justify-between">
-            <label className="block text-sm font-medium text-slate-700">
-              Configuration Values
-            </label>
-            {valuesSchema?.properties && (
-              <div className="flex gap-2">
-                <button
-                  type="button"
-                  onClick={() => setInputMethod('form')}
-                  className="cursor-pointer"
-                >
-                  <Badge
-                    variant={inputMethod === 'form' ? 'success' : 'default'}
-                    size="sm"
-                  >
-                    Form
-                  </Badge>
-                </button>
-                <button
-                  type="button"
-                  onClick={() => setInputMethod('yaml')}
-                  className="cursor-pointer"
-                >
-                  <Badge
-                    variant={inputMethod === 'yaml' ? 'success' : 'default'}
-                    size="sm"
-                  >
-                    YAML
-                  </Badge>
-                </button>
-              </div>
-            )}
-          </div>
-
-          {loadingSchema ? (
-            <LoadingState message="Loading configuration schema..." />
-          ) : inputMethod === 'form' && valuesSchema ? (
-            <SchemaFormGenerator
-              schema={valuesSchema}
-              values={formValues}
-              onChange={handleFormValuesChange}
-            />
-          ) : (
-            <Textarea
-              value={valuesYaml}
-              onChange={(e) => setValuesYaml(e.target.value)}
-              rows={12}
-              placeholder="key: value&#10;nested:&#10;  key: value"
-              className="font-mono text-sm"
-            />
-          )}
+        {/* Current Values — directly editable as YAML */}
+        <div className="space-y-2">
+          <label className="block text-sm font-medium text-slate-700">
+            Configuration Values
+          </label>
+          <p className="text-xs text-slate-500">
+            Editing current deployed values. Changes are merged with existing release values (--reuse-values).
+          </p>
+          <Textarea
+            value={valuesYaml}
+            onChange={(e) => setValuesYaml(e.target.value)}
+            rows={14}
+            placeholder="key: value&#10;nested:&#10;  key: value"
+            className="font-mono text-sm"
+          />
         </div>
 
         {/* Values Diff Section */}
@@ -415,42 +325,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
   );
 };
 
-const isJsonSchemaObject = (value: unknown): value is JsonSchema =>
-  typeof value === "object" && value !== null && !Array.isArray(value);
-
-const extractJsonSchema = (schemaResponse: unknown): JsonSchema | null => {
-  if (schemaResponse == null) {
-    return null;
-  }
-
-  const tryParse = (value: unknown): unknown => {
-    if (typeof value === "string") {
-      try {
-        return JSON.parse(value);
-      } catch {
-        return null;
-      }
-    }
-    return value;
-  };
-
-  let candidate: unknown = tryParse(schemaResponse);
-
-  if (candidate && typeof candidate === "object" && "schema" in (candidate as Record<string, unknown>)) {
-    const inner = (candidate as { schema?: unknown }).schema;
-    const normalizedInner = extractJsonSchema(inner);
-    if (normalizedInner) {
-      return normalizedInner;
-    }
-  }
-
-  if (isJsonSchemaObject(candidate)) {
-    return candidate as JsonSchema;
-  }
-
-  return null;
-};
-
 const parseValuesYaml = (source: string): Record<string, any> => {
   const parsed = parseYaml(source);
   if (parsed == null) {