feat: initial scaffold of awesome-coding-agents tracker

Go updater that fetches AI agent coding tool repo stats via GitHub GraphQL
(batched, one query), sorts by star count, appends a daily snapshot to
data/history.jsonl, and regenerates README.md from templates/readme.tmpl.
Daily workflow at .github/workflows/update.yml refreshes rankings and
commits changes. Seed list in data/agents.yml covers 19 tracked repos.

.github/workflows/update.yml

@@ -0,0 +1,49 @@
+name: Update rankings
+
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch:
+  push:
+    branches: [main]
+    paths:
+      - 'data/agents.yml'
+      - 'templates/**'
+      - '**.go'
+      - 'go.mod'
+      - '.github/workflows/update.yml'
+
+permissions:
+  contents: write
+
+concurrency:
+  group: update-rankings
+  cancel-in-progress: false
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: 'stable'
+          cache: true
+
+      - name: Run updater
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: go run .
+
+      - name: Commit changes
+        run: |
+          git config user.name  "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add README.md data/history.jsonl
+          if git diff --staged --quiet; then
+            echo "no changes"
+            exit 0
+          fi
+          git commit -m "chore: daily ranking refresh"
+          git push