security: a real CI check before auto-merge; .github/ always protected (#46)

- checks(): the worker's own time/worker-run status can block or delay a merge but never counts as green
- dispatch_ci(): with no other check on the head, Time runs TIME_CI_WORKFLOW (ci.yml, workflow_dispatch) on the PR branch and waits; beat ci-dispatched, once
- ci.yml accepts workflow_dispatch
- touches_protected(): .github/ is always protected, whatever TIME_PROTECTED says
- labs-aicharts.yml: deploy URL via env, not ${{ }} in the script
- tests: worker-status-only no longer merges; dispatch once; real context merges


Claude-Session: https://claude.ai/code/session_01CYHXFvWMCs1GUmRmpySqQ6

Co-authored-by: claude <noreply@anthropic.com>

.github/workflows/labs-aicharts.yml

@@ -25,9 +25,10 @@ jobs:
           CLOUDFLARE_ACCOUNT_ID: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
           TIME_VENTURE_DOMAIN: ${{ vars.TIME_VENTURE_DOMAIN }}
       - name: smoke
+        env:
+          u: ${{ steps.deploy.outputs.url }}   # through env, never interpolated into the script
         run: |
           set -o pipefail
-          u="${{ steps.deploy.outputs.url }}"
           for i in $(seq 1 18); do curl -fsS "${u}api/health" && break; sleep 10; done
           curl -fsS "${u}api/schema?dataset=orders" | python3 -c 'import json,sys; d=json.load(sys.stdin); assert len(d["sample"])==5, d; print("schema ok")'
           curl -fsS -X POST "${u}api/spec" -H 'content-type: application/json' \