feat: M0 monorepo skeleton with services, clients, deploy and CI

- api/openapi.yaml: contract with /healthz, /readyz, /api/v1/server-info
- services/api (Go): api with oapi-codegen strict server, goose migrations,
  readiness checks for Postgres/Redis; storage-agent stub with internal token
- services/recommender (Python, uv): FastAPI health/readiness/internal status,
  `pipu-rec serve` and `pipu-rec analyze` entrypoints
- packages: generated api-client, core (server URL + server check),
  i18n (ru/en + dictionary check), design-tokens (CSS vars + TS from tokens.json)
- apps/web: Vite + React shell showing server status, language switch
- apps/mobile: Expo (SDK 53) Android app with server connect screen
- deploy: Dockerfiles, compose (prod + dev), nginx template, install/update scripts
- .gitea/workflows: ci.yml and tag-based release.yml (images, signed APK, release)
- scripts/version.mjs: version and Android versionCode from git tag
- tests/fixtures/music/generate.sh: synthetic test library via ffmpeg
- docs: versionCode formula, OpenAPI 3.0.3, dev instructions in README

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/i18n/locales/en/common.json

@@ -0,0 +1,21 @@
+{
+  "app": {
+    "name": "pipu",
+    "tagline": "Your music from your own server"
+  },
+  "server": {
+    "title": "Server",
+    "checking": "Checking the server…",
+    "online": "Server {{version}} is online",
+    "offline": "The server is not responding. Check the address and your network.",
+    "address": "Server address",
+    "check": "Check",
+    "invalid_address": "Enter the server address, e.g. https://music.home.lan",
+    "unsupported_app": "This app version is too old for the server — please update the app"
+  },
+  "language": {
+    "label": "Language",
+    "ru": "Русский",
+    "en": "English"
+  }
+}