Add Phase 6: multi-server admin panel (server registry + settings)

Gate a new /api/admin/* route set (register/list/update/delete servers)
behind a single shared MCMAPPER_ADMIN_TOKEN header, and add a /admin
frontend page (Alpine) to unlock, register new servers, and edit
authMode/anonymousChatAllowed/waypointFormat per server — these columns
already existed but were only editable via direct DB edit until now.

Written test-first per the project's TDD workflow: admin.ts's domain
logic, the index.ts route wiring, and a new e2e/tests/admin.spec.ts
covering the token gate and register/edit/delete round trip through the
real browser UI.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015tKdPZt78zbPUZMXWzKEKt

README.md

@@ -61,20 +61,37 @@ docker compose up
 migrations on startup (see `api/src/db/migrate.ts`); `worker` consumes the `mcmapper:dirty-chunks`
 Redis stream via a consumer group (`mcmapper-workers`) so multiple instances split work safely.
 
-### Phase 1: connecting a mod instance
+### Connecting a mod instance
 
-There's no admin registration API yet (Phase 6) — seed one server row by hand, then point the
-mod's `MapperConfig` at the same token:
+Register a server via the admin panel at `/admin` (set `MCMAPPER_ADMIN_TOKEN` first — see
+"Admin panel" below), or seed one row by hand for scripted/headless setup:
 
 ```
 docker compose run --rm api bun run seed
 ```
 
 reads `MCMAPPER_SEED_SERVER_NAME`/`MCMAPPER_SEED_SERVER_TOKEN` from `api/.env.example` (edit
-those first, or override with `-e`). Once the mod connects and sends its initial chunk backfill,
-tiles appear at `GET /api/tiles/:serverId/:dimension/:zoom/:tileX/:tileY.png` (zoom is always `0`
-for now — see `worker/src/render/cpu.rs`) and the frontend's Leaflet viewer picks them up
-automatically from `GET /api/servers`.
+those first, or override with `-e`). Either way, point the mod's `MapperConfig#serverToken` at
+the resulting token. Once the mod connects and sends its initial chunk backfill, tiles appear at
+`GET /api/tiles/:serverId/:dimension/:zoom/:tileX/:tileY.png` (zoom is always `0` for now — see
+`worker/src/render/cpu.rs`) and the frontend's Leaflet viewer picks them up automatically from
+`GET /api/servers`.
+
+### Admin panel
+
+`/admin` (linked from the map page's header) manages the server registry: register new servers
+(generates their token — never admin-supplied, so it can't collide with or be guessed from
+anything else), and edit `authMode`, `anonymousChatAllowed`, and `waypointFormat` per server.
+It's gated behind a single shared secret, not a per-account role (this is a single-operator
+backend) — set `MCMAPPER_ADMIN_TOKEN` in `api/`'s untracked `.env` (see `api/.env.example`),
+restart `api`, then enter that same value into the panel's unlock prompt. Leaving it unset
+disables every `/api/admin/*` route (401), it does not default to open. The token is remembered
+in the browser's `localStorage` after unlocking, same pattern as the player-facing session token
+(see `api/src/link.ts`'s doc comment).
+
+Settings not exposed here yet (which map types render, dimension filtering, player-position
+visibility) don't have underlying features built for them either — no point in a knob nothing
+reads. They'll gain admin UI alongside the feature that needs them.
 
 ## Running tests
 
@@ -121,12 +138,14 @@ bunx playwright test
 (unlike the `bun test` section above): throwaway Postgres/Redis/MinIO containers
 (`mcmapper-e2e-*`, distinct names/ports from the `bun test` ones so both can run at once),
 migrations, a seeded server + linked account/session + a 5x5-chunk terrain footprint around the
-world origin, then the `api`/`frontend`/proxy processes. `global-teardown.ts` kills every spawned
-process and removes the containers afterward. Covers the two UI flows most worth a real
-click-through: the marker click-to-place/edit popup (`tests/markers.spec.ts`, including that a
-marker created while linked shows up in a second browser context with the same session — the
-cross-device sync claim) and the region-select drag + glTF export (`tests/region-export.spec.ts`,
-including a real triggered file download).
+world origin, then the `api`/`frontend`/proxy processes (the `api` process is started with a
+fixed `MCMAPPER_ADMIN_TOKEN` for `tests/admin.spec.ts` to use — see `config.ts`'s `ADMIN_TOKEN`).
+`global-teardown.ts` kills every spawned process and removes the containers afterward. Covers the
+UI flows most worth a real click-through: the marker click-to-place/edit popup
+(`tests/markers.spec.ts`, including that a marker created while linked shows up in a second
+browser context with the same session — the cross-device sync claim), the region-select drag +
+glTF export (`tests/region-export.spec.ts`, including a real triggered file download), and the
+admin panel's token gate + server register/edit/delete round trip (`tests/admin.spec.ts`).
 
 ## Attribution