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>

api/openapi.yaml

@@ -0,0 +1,129 @@
+openapi: 3.0.3
+info:
+  title: Pipu Music API
+  version: 0.1.0
+  description: |
+    Публичный REST API Pipu Music. Источник истины для сервера (oapi-codegen)
+    и клиентов (openapi-typescript). Соглашения — docs/api.md.
+servers:
+  - url: /
+tags:
+  - name: system
+paths:
+  /healthz:
+    get:
+      operationId: getHealthz
+      tags: [system]
+      summary: Живость процесса
+      responses:
+        "200":
+          description: Процесс жив
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/HealthStatus"
+  /readyz:
+    get:
+      operationId: getReadyz
+      tags: [system]
+      summary: Готовность обслуживать запросы (зависимости доступны)
+      responses:
+        "200":
+          description: Все зависимости доступны
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ReadyStatus"
+        "503":
+          description: Одна или несколько зависимостей недоступны
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ReadyStatus"
+  /api/v1/server-info:
+    get:
+      operationId: getServerInfo
+      tags: [system]
+      summary: Сведения о сервере для клиентов
+      description: |
+        Вызывается без аутентификации: веб и Android проверяют версию сервера,
+        совместимость клиента и поддерживаемые языки (экран подключения).
+      responses:
+        "200":
+          description: Сведения о сервере
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ServerInfo"
+        default:
+          $ref: "#/components/responses/Problem"
+components:
+  responses:
+    Problem:
+      description: Ошибка (RFC 9457)
+      content:
+        application/problem+json:
+          schema:
+            $ref: "#/components/schemas/Problem"
+  schemas:
+    HealthStatus:
+      type: object
+      required: [status]
+      properties:
+        status:
+          type: string
+          enum: [ok]
+    ReadyStatus:
+      type: object
+      required: [status, checks]
+      properties:
+        status:
+          type: string
+          enum: [ok, degraded]
+        checks:
+          type: object
+          description: Результат проверки каждой зависимости
+          additionalProperties:
+            type: string
+            description: "`ok` или текст ошибки"
+    ServerInfo:
+      type: object
+      required: [name, version, api_version, supported_locales, min_android_version_code]
+      properties:
+        name:
+          type: string
+          example: pipu-music
+        version:
+          type: string
+          description: Версия сервера (SemVer)
+          example: 0.1.0
+        api_version:
+          type: string
+          example: v1
+        supported_locales:
+          type: array
+          items:
+            type: string
+          example: [ru, en]
+        min_android_version_code:
+          type: integer
+          description: Минимальный versionCode Android-приложения, которое поддерживает сервер
+          example: 10099
+    Problem:
+      type: object
+      required: [status, code]
+      properties:
+        type:
+          type: string
+          default: about:blank
+        status:
+          type: integer
+        code:
+          type: string
+          description: Машинный код ошибки для i18n, например `auth.invalid_credentials`
+        detail:
+          type: string
+          description: Пояснение для логов (не для показа пользователю)
+        params:
+          type: object
+          additionalProperties: true