Rename castle-app to libra-app

Match the upstream LNbits extension rebrand (Castle Accounting → Libra).
Renames the standalone PWA build artifacts and all references:

- castle.html → libra.html
- vite.castle.config.ts → vite.libra.config.ts (PWA name "Libra —
  Team Accounting", short_name "Libra", manifest id libra-accounting)
- npm scripts: build:castle/dev:castle/preview:castle → build:libra
  etc; dev:all and build:demo chains updated; dist-castle → dist-libra
- Hub tile: Lucide icon Castle → Scale (the scales/balance metaphor),
  label "Castle" → "Libra", env var VITE_HUB_CASTLE_URL → VITE_HUB_LIBRA_URL
- ExpensesAPI: /castle/api/v1/* → /libra/api/v1/* (matches the renamed
  LNbits extension's URL prefix)
- Feature flags VITE_CASTLE_INCOME_ENABLED/VITE_CASTLE_BUDGETS_ENABLED →
  VITE_LIBRA_*
- i18n: top-level "castle" namespace → "libra" across en/es/fr; all
  t('castle.*') usages updated
- localStorage key castle-expense-drafts → libra-expense-drafts
- nginx.conf.example: /castle/ routes + castle.<domain> redirect → libra
- Comments and identifiers: castleOwesUser → libraOwesUser, castle.api
  references in docs

Source dir src/accounting-app/ stays as-is (already feature-named, not
brand-named).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -12,9 +12,9 @@
     "dev:activities": "vite --host --config vite.activities.config.ts",
     "build:activities": "vue-tsc -b && vite build --config vite.activities.config.ts",
     "preview:activities": "vite preview --host --config vite.activities.config.ts",
-    "dev:castle": "vite --host --config vite.castle.config.ts",
-    "build:castle": "vue-tsc -b && vite build --config vite.castle.config.ts",
-    "preview:castle": "vite preview --host --config vite.castle.config.ts",
+    "dev:libra": "vite --host --config vite.libra.config.ts",
+    "build:libra": "vue-tsc -b && vite build --config vite.libra.config.ts",
+    "preview:libra": "vite preview --host --config vite.libra.config.ts",
     "dev:wallet": "vite --host --config vite.wallet.config.ts",
     "build:wallet": "vue-tsc -b && vite build --config vite.wallet.config.ts",
     "preview:wallet": "vite preview --host --config vite.wallet.config.ts",
@@ -30,8 +30,8 @@
     "dev:forum": "vite --host --config vite.forum.config.ts",
     "build:forum": "vue-tsc -b && vite build --config vite.forum.config.ts",
     "preview:forum": "vite preview --host --config vite.forum.config.ts",
-    "dev:all": "concurrently -n hub,castle,sortir,wallet,chat,forum,market,tasks -c blue,magenta,cyan,yellow,green,blue,red,gray \"npm:dev\" \"npm:dev:castle\" \"npm:dev:activities\" \"npm:dev:wallet\" \"npm:dev:chat\" \"npm:dev:forum\" \"npm:dev:market\" \"npm:dev:tasks\"",
-    "build:demo": "npm run build && VITE_BASE_PATH=/sortir/ npm run build:activities && VITE_BASE_PATH=/castle/ npm run build:castle && VITE_BASE_PATH=/wallet/ npm run build:wallet && VITE_BASE_PATH=/chat/ npm run build:chat && VITE_BASE_PATH=/forum/ npm run build:forum && VITE_BASE_PATH=/market/ npm run build:market && VITE_BASE_PATH=/tasks/ npm run build:tasks",
+    "dev:all": "concurrently -n hub,libra,sortir,wallet,chat,forum,market,tasks -c blue,magenta,cyan,yellow,green,blue,red,gray \"npm:dev\" \"npm:dev:libra\" \"npm:dev:activities\" \"npm:dev:wallet\" \"npm:dev:chat\" \"npm:dev:forum\" \"npm:dev:market\" \"npm:dev:tasks\"",
+    "build:demo": "npm run build && VITE_BASE_PATH=/sortir/ npm run build:activities && VITE_BASE_PATH=/libra/ npm run build:libra && VITE_BASE_PATH=/wallet/ npm run build:wallet && VITE_BASE_PATH=/chat/ npm run build:chat && VITE_BASE_PATH=/forum/ npm run build:forum && VITE_BASE_PATH=/market/ npm run build:market && VITE_BASE_PATH=/tasks/ npm run build:tasks",
     "electron:dev": "concurrently \"vite --host\" \"electron-forge start\"",
     "electron:build": "vue-tsc -b && vite build && electron-builder",
     "electron:package": "electron-builder",