e2e: shared auth + journal seed helpers; flag unregistered specs

The virtual-authenticator setup and registerUser were copy-pasted into
six spec files and had drifted: the auth spec's copy lost the final
URL assertion, and the settings spec's variant skipped hydration and
the Terms checkbox entirely. Seed-route boilerplate and hardcoded
localhost URLs were repeated across three more files.

- helpers/auth.ts: setup/removeVirtualAuthenticator,
  submitRegistration (no outcome assertion, for expected-failure
  attempts), registerUser (asserts the signed-in redirect),
  registerFreshUser, logout
- helpers/journal.ts: JOURNAL/PLANNER base URLs, seedRoute,
  routeHasGeom, seedKomootConnection
- nine spec files now import the helpers instead of re-deriving them

Found while consolidating: settings.test.ts, explore.test.ts, and
social.test.ts are not matched by any playwright project and have
never run — which is how the settings spec's broken register helper
survived. Registering them (and fixing whatever has rotted) is a
follow-up; the config now carries a warning so the trap is at least
documented.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

playwright.config.ts

@@ -14,6 +14,9 @@ export default defineConfig({
     trace: "on-first-retry",
     screenshot: "only-on-failure",
   },
+  // NOTE: specs only run if a project below matches them — a new
+  // e2e/*.test.ts file MUST be registered here or it silently never
+  // executes (settings/explore/social sat unregistered for months).
   projects: [
     {
       name: "journal",