Add GET/POST /competitors/config/system endpoints for Settings page

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/api/competitors.py

@@ -144,6 +144,40 @@ async def get_scraper_status(
     )
 
 
+@router.get("/config/system")
+async def get_system_config(
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user)
+):
+    """Return all system_config rows as a flat dict."""
+    result = await db.execute(text("SELECT config_key, config_value FROM system_config"))
+    return {row.config_key: row.config_value for row in result.fetchall()}
+
+
+class SystemConfigUpdate(BaseModel):
+    key: str
+    value: str
+
+
+@router.post("/config/system")
+async def set_system_config(
+    payload: SystemConfigUpdate,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user)
+):
+    """Upsert a single system_config key."""
+    await db.execute(
+        text("""
+            INSERT INTO system_config (config_key, config_value)
+            VALUES (:key, :value)
+            ON CONFLICT (config_key) DO UPDATE SET config_value = EXCLUDED.config_value
+        """),
+        {'key': payload.key, 'value': payload.value}
+    )
+    await db.commit()
+    return {"status": "success", "key": payload.key}
+
+
 @router.post("/config/location")
 async def set_location_config(
     config: LocationConfigRequest,