ci: harden contributor checks (#254)

* ci: harden contributor checks

* ci: pin setup-uv action release

* ci: split workflow checks

* docs: clarify required checks

.github/workflows/ci.yml

@@ -2,7 +2,7 @@ name: CI
 
 on:
   push:
-    branches: [main, dev, master]
+    branches: [main]
   pull_request:
 
 # Cancel superseded runs on the same ref to save CI minutes.
@@ -14,14 +14,14 @@ permissions:
   contents: read
 
 jobs:
-  ci:
-    name: lint + test + integration
+  lint:
+    name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v4
+        uses: astral-sh/setup-uv@v8.2.0
         with:
           enable-cache: true
           cache-dependency-glob: uv.lock
@@ -35,8 +35,62 @@ jobs:
       - name: Lint (ruff + import-linter + datetime + openapi drift)
         run: make lint
 
+  unit:
+    name: unit tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v8.2.0
+        with:
+          enable-cache: true
+          cache-dependency-glob: uv.lock
+
+      - name: Set up Python
+        run: uv python install 3.12
+
+      - name: Install dependencies (frozen)
+        run: make install-deps
+
       - name: Unit tests
         run: make test
 
+  integration:
+    name: integration tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v8.2.0
+        with:
+          enable-cache: true
+          cache-dependency-glob: uv.lock
+
+      - name: Set up Python
+        run: uv python install 3.12
+
+      - name: Install dependencies (frozen)
+        run: make install-deps
+
       - name: Integration tests
         run: make integration
+
+  package:
+    name: package build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v8.2.0
+        with:
+          enable-cache: true
+          cache-dependency-glob: uv.lock
+
+      - name: Set up Python
+        run: uv python install 3.12
+
+      - name: Build and smoke-test package
+        run: make package