ci: commit version bump directly via @semantic-release/git

Replace the bespoke bump-version action + PR flow with the standard
@semantic-release/git plugin. semantic-release now commits the version
bump (package.json, package-lock.json, app/manifest.json, CHANGELOG.md)
straight to master as part of the release job, eliminating the
housekeeping PR that had to be reviewed and merged manually after
every release.

- Add @semantic-release/git to .releaserc.json (dependency was already
  declared in devDependencies at ^10.0.1)
- Remove the 'Bump Version' step and pull-requests write permission
  from the release workflow
- Delete the now-unreachable .github/actions/bump-version action

Author: kgogov

.github/actions/bump-version/action.yml

@@ -11,7 +11,6 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
-      pull-requests: write
     steps:
       - uses: actions/checkout@v6
       - name: Setup Node.js
@@ -22,12 +21,11 @@ jobs:
         run: npm ci
       - name: Run tests
         run: grunt test
-      # Release using semantic-relaease if there are new smenatic commits
+      # Release using semantic-release if there are new semantic commits.
+      # The @semantic-release/git plugin commits the version bump
+      # (package.json, package-lock.json, app/manifest.json, CHANGELOG.md)
+      # directly back to master.
       - name: Release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: npx semantic-release
-      - name: Bump Version
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        uses: ./.github/actions/bump-version

.github/actions/bump-version/index.js

@@ -9,6 +9,18 @@
           "prepareCmd": "node ./scripts/update-version.js ${nextRelease.version} && npm i"
         }
     ],
+    [
+      "@semantic-release/git",
+      {
+        "assets": [
+          "package.json",
+          "package-lock.json",
+          "app/manifest.json",
+          "CHANGELOG.md"
+        ],
+        "message": "chore(release): ${nextRelease.version} [skip ci]\n\n${nextRelease.notes}"
+      }
+    ],
     [
       "@semantic-release/github",
       {