Add star history chart, hourly workflow and index page

stars.mjs renders dist/<owner>/<repo>.svg for each repo in repos.txt:
a cumulative star chart with labelled breakouts, spikes and first star,
ending in an isometric star. The hourly workflow commits only when the
star count or UTC day changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/stars.yml

@@ -0,0 +1,24 @@
+name: stars
+on:
+  schedule:
+    - cron: '17 * * * *'
+  workflow_dispatch:
+permissions:
+  contents: write
+concurrency: stars
+jobs:
+  render:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-node@v7
+        with:
+          node-version: 24
+      - run: node stars.mjs
+        env:
+          GITHUB_TOKEN: ${{ secrets.STARS_TOKEN || github.token }}
+      - run: |
+          git add dist
+          git diff --cached --quiet && exit 0
+          git -c user.name='github-actions[bot]' -c user.email='41898282+github-actions[bot]@users.noreply.github.com' commit -m 'Update star charts'
+          git push