test(guard): no legacy list left; flag raw listeners on a fixed port (#440)

With the sweep done, LEGACY_FIXED_PORT_FILES and its staleness test go. A second rule flags a raw listen(<number or …PORT>) and a port: with a number or …PORT constant inside listen({ … }) or new WebSocketServer({ … }); a socket path and a lower-case variable pass. CLAUDE.md, AGENTS.md, CONTRIBUTING.md and the wiki's Contributing page lose the mobile exception, and CLAUDE.md names closedPort() instead of port + 1.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -12,6 +12,6 @@ Quick pointers:
 
 - Type check: `tsc --noEmit` · Lint: `npm run lint` · Format: `npm run format:check`
 - Tests: `npm test` (the CI gate, safe to run bare) or `npm test -- test/<file>.test.ts` for one file
-- Route tests use `app.inject()`; new tests needing a socket bind port 0 (`new WebServer(0, …)` + `boundPort`), except mobile tests, which keep `createTestServer(PORT)` for now
+- Route tests use `app.inject()`; new tests needing a socket bind port 0 (`new WebServer(0, …)` + `boundPort`); mobile tests use `createTestServer()` and read `server.boundPort`
 - Branch off `master` for all work; Conventional Commit-style messages (`fix(mobile): ...`)
 - Never commit secrets or local state from `~/.codeman/`