ci: replace tag-triggered release with release-please

Switch from manual v* tag workflow to googleapis/release-please-action.
Conventional commits on main now auto-maintain a Release PR with
changelog and version bump. Merging that PR triggers uv build + PyPI
publish.

Author: rchardx

.github/workflows/release.yml

@@ -1,14 +1,30 @@
-name: Release to PyPI
+name: Release
 
 on:
   push:
-    tags: ["v*"]
+    branches: [main]
+
+permissions:
+  contents: write
+  pull-requests: write
 
 jobs:
-  release:
+  release-please:
+    runs-on: ubuntu-latest
+    outputs:
+      release_created: ${{ steps.release.outputs.release_created }}
+      tag_name: ${{ steps.release.outputs.tag_name }}
+    steps:
+      - uses: googleapis/release-please-action@v4
+        id: release
+        with:
+          config-file: release-please-config.json
+          manifest-file: .release-please-manifest.json
+
+  publish:
+    needs: release-please
+    if: ${{ needs.release-please.outputs.release_created }}
     runs-on: ubuntu-latest
-    permissions:
-      contents: write
     steps:
       - uses: actions/checkout@v4
 
@@ -17,8 +33,3 @@ jobs:
       - run: uv build
 
       - run: uv publish --token ${{ secrets.PYPI_TOKEN }}
-
-      - name: Create GitHub Release
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: gh release create "${{ github.ref_name }}" dist/* --generate-notes

.release-please-manifest.json

@@ -0,0 +1,3 @@
+{
+  ".": "0.2.0"
+}

release-please-config.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
+  "release-type": "python",
+  "include-v-in-tag": true,
+  "bump-minor-pre-major": true,
+  "bump-patch-for-minor-pre-major": true,
+  "packages": {
+    ".": {
+      "package-name": "opencode-usage",
+      "extra-files": [
+        {
+          "type": "toml",
+          "path": "pyproject.toml",
+          "jsonpath": "$.project.version"
+        }
+      ],
+      "changelog-sections": [
+        { "type": "feat", "section": "Features" },
+        { "type": "fix", "section": "Bug Fixes" },
+        { "type": "refactor", "section": "Code Refactoring" },
+        { "type": "perf", "section": "Performance Improvements" },
+        { "type": "docs", "section": "Documentation" },
+        { "type": "test", "section": "Tests", "hidden": true },
+        { "type": "chore", "section": "Miscellaneous", "hidden": true },
+        { "type": "ci", "section": "CI", "hidden": true },
+        { "type": "style", "section": "Styles", "hidden": true }
+      ]
+    }
+  }
+}