ci(web): Phase P6 — vite build in PR CI + headless E2E gate on trunk publishes (#1445)

- ci.yml: build step (vite build via turbo) runs on every PR pipeline after test
- publish.yml: e2e step boots the gateway from built dist (HOME/cwd-isolated
  throwaway PGlite) and runs the Playwright suite headless inside
  mcr.microsoft.com/playwright:v1.58.2-noble against the SPA bundle served
  exactly as production serves it; both kaniko publishes now gate on e2e
- serve-spa.ts: strip query strings before asset resolution; immutable
  cache-control for hashed assets (onSend hook); e2e spec covers both
- e2e suite hardened: globalSetup seeds admin+member through real
  bootstrap/better-auth APIs (Origin header for CSRF), loginAs waits for the
  post-login redirect (fixes 27-skipped race), stale #152-era assertions
  rewritten to the current command-driven UI, strict-mode violations fixed
  with level-1 heading queries and .or() auto-retrying locators
- verify-release mirrors the new build stage; playwright artifacts ignored

.gitignore

@@ -23,3 +23,7 @@ infra/step-ca/dev-password
 # traversal error: ... .timestamp-*.mjs: No such file or directory" when the
 # file vanished mid-scan. Ignoring them removes the race.
 *.timestamp-*.mjs
+
+# Playwright run artifacts (#1445, P6 E2E gate)
+apps/web/test-results/
+apps/web/playwright-report/