Add image upload and vision analysis to Ask Simba chat

Users can now attach images in the web chat for Simba to analyze using
Ollama's gemma3 vision model. Images are stored in Garage (S3-compatible)
and displayed in chat history.

Also fixes aerich migration config by extracting TORTOISE_CONFIG into a
standalone config/db.py module, removing the stale aerich_config.py, and
adding missing MODELS_STATE to migration 3.

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

app.py

@@ -13,6 +13,7 @@ import blueprints.users
 import blueprints.whatsapp
 import blueprints.email
 import blueprints.users.models
+from config.db import TORTOISE_CONFIG
 from main import consult_simba_oracle
 
 # Load environment variables
@@ -28,6 +29,7 @@ app = Quart(
 )
 
 app.config["JWT_SECRET_KEY"] = os.getenv("JWT_SECRET_KEY", "SECRET_KEY")
+app.config["MAX_CONTENT_LENGTH"] = 10 * 1024 * 1024  # 10 MB upload limit
 jwt = JWTManager(app)
 
 # Register blueprints
@@ -38,24 +40,6 @@ app.register_blueprint(blueprints.whatsapp.whatsapp_blueprint)
 app.register_blueprint(blueprints.email.email_blueprint)
 
 
-# Database configuration with environment variable support
-DATABASE_URL = os.getenv(
-    "DATABASE_URL", "postgres://raggr:raggr_dev_password@localhost:5432/raggr"
-)
-
-TORTOISE_CONFIG = {
-    "connections": {"default": DATABASE_URL},
-    "apps": {
-        "models": {
-            "models": [
-                "blueprints.conversation.models",
-                "blueprints.users.models",
-                "aerich.models",
-            ]
-        },
-    },
-}
-
 # Initialize Tortoise ORM with lifecycle hooks
 @app.while_serving
 async def lifespan():