feat: add WonderQ admin backend

Add FastAPI admin/public API service, database setup, Docker deployment files, docs, and tests.

app/config.py

@@ -0,0 +1,29 @@
+from functools import lru_cache
+from urllib.parse import parse_qsl, urlencode, urlsplit, urlunsplit
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    database_url: str = Field(default="postgresql://miniapp:miniapp_dev_password@localhost:5433/miniapp")
+    jwt_secret: str = Field(default="dev-only-change-me-before-production")
+    jwt_expires_hours: int = Field(default=8)
+    log_level: str = Field(default="info")
+    port: int = Field(default=4000)
+    cors_origins: str = Field(default="*")
+
+    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
+
+    @property
+    def sqlalchemy_url(self) -> str:
+        parsed = urlsplit(self.database_url)
+        query = urlencode([(key, value) for key, value in parse_qsl(parsed.query, keep_blank_values=True) if key != "schema"])
+        normalized = urlunsplit((parsed.scheme, parsed.netloc, parsed.path, query, parsed.fragment))
+        if normalized.startswith("postgresql://"):
+            return normalized.replace("postgresql://", "postgresql+psycopg://", 1)
+        return normalized
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()