docs(260618-smr): remove Redis references from documentation and e2e config

- CLAUDE.md: remove Redis constraint, ioredis library row, Redis architecture sentence, update compose comment
- README.md: remove Redis from prereqs, quick-start command, compose description, tech-stack live-sync row
- docs/ARCHITECTURE.md: delete Redis infrastructure table row
- docs/CONFIGURATION.md: remove Redis localhost:6379 mention from dev section
- docs/deployment.md: delete redis services table row
- docs/DEVELOPMENT.md: remove prereq mention, heading, two up commands, expose bullet, stack comment
- docs/GETTING-STARTED.md: prereq row, up command, prose mention
- docs/TESTING.md: 'API and MariaDB' (was API, MariaDB, and Redis)
- apps/pwa/e2e/README.md: delete Redis on :6379 bullet
- apps/pwa/playwright.config.ts: two comments updated (API+MariaDB, not API+MariaDB+Redis)

docs/ARCHITECTURE.md

@@ -248,7 +248,6 @@ routes/setup.ts   ──→  db (app_config)
 | Local auth storage   | scrypt PHC hash in `local_credentials.password_hash`; session signed with `LOCAL_SESSION_SECRET` env var                    |
 | Push notifications   | `web-push` (VAPID) → APNs (iOS) / FCM (Android)                                                                             |
 | Live list sync       | In-process Node.js `EventEmitter` → SSE (`text/event-stream`)                                                               |
-| Redis                | Present in stack (image: `redis:7-alpine`); not used in current runtime (reserved for future multi-process pub/sub)         |
 | PWA                  | React 19 + Vite 8 + `vite-plugin-pwa` (Workbox `injectManifest` mode)                                                       |
 | Networking           | Pangolin/Newt tunnel — no open ports; split-DNS internal domain                                                             |
 | Deployment           | Docker Compose on Unraid; single `api` container serves both the API and the PWA static build                               |