delete the landing app

Built and shipped from somewhere else now, so this copy was dead weight that still
carried its own third copy of the palette — `duck-teal` had three different definitions
across three apps, and this was one of them.

Removed: `src/apps/landing`, `scripts/build/landing.ts`, the `build:landing` script,
and the tree entry in CLAUDE.md.

`/landing-page-data` STAYS and is unrelated despite the name — it is the API the
sign-in screen asks whether registration is open. Worth saying because a grep for
"landing" hits both and only one of them was meant.

Nothing imported from the app. tsgo clean, frontend builds, the live app serves.

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

CLAUDE.md

@@ -80,8 +80,7 @@ deliberate — it is the owner's own machine. Do not add a jail without being as
 src/
 ├── server.tsx              # the single entrypoint: routes, WS upgrades, static files
 ├── apps/
-│   ├── officer-web/        # the SPA shell — Screens/Authentication + Screens/Dashboard
-│   └── landing/            # marketing landing page
+│   └── officer-web/        # the SPA shell — Screens/Authentication + Screens/Dashboard
 ├── servers/
 │   ├── hono.ts             # router composition; everything under /api
 │   ├── _middlewares/       # auth, body parsing, the permission gate, rate limiting