feat: implement AI model API proxy service

backend/app/database.py

@@ -0,0 +1,84 @@
+"""Database connection and initialization."""
+import aiosqlite
+from pathlib import Path
+from contextlib import asynccontextmanager
+
+DB_PATH = Path(__file__).parent.parent / "data" / "zzrouter.db"
+
+
+async def get_db() -> aiosqlite.Connection:
+    """Get database connection."""
+    DB_PATH.parent.mkdir(parents=True, exist_ok=True)
+    conn = await aiosqlite.connect(DB_PATH)
+    conn.row_factory = aiosqlite.Row
+    return conn
+
+
+@asynccontextmanager
+async def db_connection():
+    """Context manager for database connection."""
+    conn = await get_db()
+    try:
+        yield conn
+    finally:
+        await conn.close()
+
+
+async def init_db():
+    """Initialize database schema."""
+    async with db_connection() as db:
+        await db.executescript("""
+            CREATE TABLE IF NOT EXISTS client_keys (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                key TEXT UNIQUE NOT NULL,
+                name TEXT,
+                is_active BOOLEAN DEFAULT TRUE,
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            );
+
+            CREATE TABLE IF NOT EXISTS providers (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                name TEXT UNIQUE NOT NULL,
+                base_url TEXT NOT NULL,
+                api_type TEXT NOT NULL,
+                is_active BOOLEAN DEFAULT TRUE
+            );
+
+            CREATE TABLE IF NOT EXISTS provider_keys (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                provider_id INTEGER NOT NULL REFERENCES providers(id),
+                key TEXT NOT NULL,
+                is_active BOOLEAN DEFAULT TRUE,
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            );
+
+            CREATE TABLE IF NOT EXISTS request_logs (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                client_key_id INTEGER REFERENCES client_keys(id),
+                provider_id INTEGER REFERENCES providers(id),
+                model TEXT,
+                prompt_tokens INTEGER,
+                completion_tokens INTEGER,
+                latency_ms INTEGER,
+                success BOOLEAN,
+                error_message TEXT,
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            );
+
+            CREATE INDEX IF NOT EXISTS idx_request_logs_created_at ON request_logs(created_at);
+            CREATE INDEX IF NOT EXISTS idx_request_logs_client_key_id ON request_logs(client_key_id);
+        """)
+        await db.commit()
+
+
+async def seed_default_providers():
+    """Seed default providers if not exist."""
+    async with db_connection() as db:
+        await db.executemany(
+            """INSERT OR IGNORE INTO providers (name, base_url, api_type) VALUES (?, ?, ?)""",
+            [
+                ("openai", "https://api.openai.com/v1", "openai"),
+                ("anthropic", "https://api.anthropic.com/v1", "anthropic"),
+            ]
+        )
+        await db.commit()