fix: scale replicas in response, K8s metrics client, quota precheck, auth tests

- Add GetMetrics method to MetricsClient interface and implement cluster metrics API
- Add QuotaPrecheck service for validating resource quotas before deployment
- Add auth DTO with role/permission models and auth handler tests
- Add instance diagnostics: mounted NFS volumes, labels, annotations in pod diagnostics
- Update workspace handler with GetWorkspace endpoint and shared-user list
- Fix monitoring handler to use correct service method name
- Add tail_lines fallback in instance handler for snake_case query params
- Update nginx config for SSE log streaming support (no buffering)
- Add comprehensive test coverage: auth_service_test, auth_handler_test,
  auth_dto_test, metrics_client_test, quota_precheck_test
- Update error messages for quota validation and instance operations
- ModifyModal: fix YAML lineWidth:0, modified keys summary, delta-only submit
- InstanceCard: correctly disable scale-minus when replicas <= 0
- SidebarLayout: add hover transition for sidebar items
- Update todo.md and lessons.md with latest fixes

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

@@ -35,7 +35,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
   const [valuesYaml, setValuesYaml] = useState("");
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
-  const [originalValuesYaml, setOriginalValuesYaml] = useState("");
   const [modifiedKeys, setModifiedKeys] = useState<string[]>([]);
 
   // Values Diff support
@@ -60,7 +59,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
           if (data?.current && Object.keys(data.current).length > 0) {
             const currentYaml = stringifyYaml(data.current, { lineWidth: 0 });
             setValuesYaml(currentYaml);
-            setOriginalValuesYaml(currentYaml);
             setDiffData({ current: data.current, defaults: data.defaults ?? {} });
           }
         } catch (err) {
@@ -71,7 +69,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
             if (detail.values && Object.keys(detail.values).length > 0) {
               const y = stringifyYaml(detail.values, { lineWidth: 0 });
               setValuesYaml(y);
-              setOriginalValuesYaml(y);
             }
           } catch (err2) {
             console.error('[ModifyModal] Failed to load instance detail:', err2);
@@ -143,29 +140,18 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
     });
   };
 
-  const computeDeltaValues = (): Record<string, any> | undefined => {
-    if (!valuesYaml.trim()) return undefined;
-    try {
-      const current = parseYaml(valuesYaml);
-      if (!originalValuesYaml) return current; // no original to compare against
-      const original = parseYaml(originalValuesYaml);
-      return diffObjects(current, original);
-    } catch {
-      return parseValuesYaml(valuesYaml);
-    }
-  };
-
   const handleSubmit = async (e: React.FormEvent) => {
     e.preventDefault();
     setLoading(true);
     setError(null);
 
     try {
-      const deltaValues = computeDeltaValues();
+      if (valuesYaml.trim()) {
+        parseValuesYaml(valuesYaml);
+      }
       const payload: UpdateInstanceRequest = {
         version: tag && tag !== instance.version ? tag : undefined,
         description: description.trim() || undefined,
-        values: deltaValues,
         valuesYaml: valuesYaml.trim() || undefined,
       };
 
@@ -268,7 +254,7 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
             Configuration Values
           </label>
           <p className="text-xs text-slate-500">
-            Editing current deployed values. Only modified keys are sent to the server.
+            Editing current deployed values. The full YAML is submitted so nested chart values stay intact.
           </p>
           {modifiedKeys.length > 0 && (
             <div className="flex flex-wrap items-center gap-1.5 text-xs">
@@ -368,27 +354,6 @@ export const ModifyModal: React.FC<ModifyModalProps> = ({
   );
 };
 
-/** Deep diff: returns only keys in `current` whose values differ from `original` */
-const diffObjects = (current: Record<string, any>, original: Record<string, any>): Record<string, any> => {
-  const delta: Record<string, any> = {};
-  for (const key of Object.keys(current)) {
-    const cv = current[key];
-    const ov = original[key];
-    if (JSON.stringify(cv) !== JSON.stringify(ov)) {
-      if (typeof cv === 'object' && cv !== null && !Array.isArray(cv) &&
-          typeof ov === 'object' && ov !== null && !Array.isArray(ov)) {
-        const nested = diffObjects(cv, ov);
-        if (Object.keys(nested).length > 0) {
-          delta[key] = nested;
-        }
-      } else {
-        delta[key] = cv;
-      }
-    }
-  }
-  return delta;
-};
-
 const parseValuesYaml = (source: string): Record<string, any> => {
   const parsed = parseYaml(source);
   if (parsed == null) {