feat(landing): rename crew to "El valle" + source downloads from launcher.json

Rename all "crew" mentions (en/es/eu) to the untranslated proper name
"El valle" across hero, members, and features copy in i18n/ui.ts.

Rewire the homepage launcher download list to the custom-launcher build
output launcher.json (productName/version/files[]) instead of the
never-produced launcher-manifest.json shape. site.ts now reads launcher.json
and normalizes files[] -> internal builds[]; launcher.example.json is the
committed fallback. Drop the stale launcher-manifest.example/schema, update
.gitignore and docs (CLAUDE.md, plan/18).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -137,9 +137,10 @@ mirrored at apex `/launcher/`. Per guest:
 Full design settled across WS1–WS6; all tasks unchecked, ready to execute.
 - [ ] **WS1 — Join flow off packwiz.** Homepage = UlicraftLauncher, 3 steps
   (register → download launcher → join); drop `packwizUrl` + packwiz step.
-  Per-OS downloads from a synced `launcher-manifest.json` (contract:
-  `landing/src/data/launcher-manifest.schema.json`, produced by the
-  `custom-launcher` repo). Fjord moves to its own `/fjord` page.
+  Per-OS downloads from a synced `launcher.json` (shape
+  `productName/version/files[]`, the build output of the `custom-launcher`
+  repo; `launcher.example.json` committed as the documented fallback). Fjord
+  moves to its own `/fjord` page.
 - [ ] **WS2/3 — Player rosters.** Online (mc-status, live) + all-registered (new
   `mc-status /api/mcstatus/players`, admin-login → Drasl `GET /players`, ~60s
   cache). Shared avatar tile, `AVATAR_MODE` env (default `headiso`). Admin creds