ci(e2e): apply migrations, serve prod build, skip LLM specs without a key

Three fixes that take the suite from ~everything-failing to green (verified end
to end against a local stack):

1. schema.sql lags the migrations (missing e.g. workflow_open_source_submissions,
   which GET /workflows/:id queries → 500). Apply every dated migration on top of
   schema.sql (idempotent; 0 errors on a fresh DB), grant service_role AFTER so
   new tables are covered, then reload PostgREST. Fixes the workflow specs.

2. Serve a production build (next build + next start) instead of next dev. The dev
   server's on-demand compilation (slow first hit → waitForResponse timeouts) and
   hydration-error overlay (injects nextjs__container_errors DOM that pollutes text
   locators, e.g. getByText('All') matching 'Call Stack') made the suite flaky.
   Fixes tabular-reviews list render + the timing flakes.

3. LLM-dependent specs (chat rename/delete/submit, critical-path) require a model
   key to send a message. Guard them with test.skip(!hasLlmKey) (e2e/llm.ts) and
   expose ANTHROPIC_API_KEY to the Playwright process, so a keyless run is green on
   the ~23 other specs and the LLM specs run + enforce only when the secret is set.

Local result (no key, with MinIO+LibreOffice as on ubuntu-latest): 23 passed,
4 skipped, 0 failed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>