ci: add automated version bump, tag, and release script

Add scripts/release.sh that infers bump type from conventional commits
(major/minor/patch), bumps package.json, commits, tags, and pushes.
Includes safety checks for branch, clean tree, and remote sync.

Also adds a workflow_dispatch GitHub Actions workflow (bump.yml) and
Makefile targets (release, release-patch, release-minor, release-major).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/bump.yml

@@ -0,0 +1,37 @@
+name: Bump & Release
+
+on:
+  workflow_dispatch:
+    inputs:
+      bump:
+        description: 'Override bump type (leave empty to auto-detect)'
+        required: false
+        type: choice
+        options:
+          - ''
+          - patch
+          - minor
+          - major
+
+jobs:
+  bump:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Configure git
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+
+      - name: Run release script
+        run: bash scripts/release.sh ${{ github.event.inputs.bump }}