Add distributed agent architecture for multi-node signal intelligence

Features:
- Standalone agent server (intercept_agent.py) for remote sensor nodes
- Controller API blueprint for agent management and data aggregation
- Push mechanism for agents to send data to controller
- Pull mechanism for controller to proxy requests to agents
- Multi-agent SSE stream for combined data view
- Agent management page at /controller/manage
- Agent selector dropdown in main UI
- GPS integration for location tagging
- API key authentication for secure agent communication
- Integration with Intercept's dependency checking system

New files:
- intercept_agent.py: Remote agent HTTP server
- intercept_agent.cfg: Agent configuration template
- routes/controller.py: Controller API endpoints
- utils/agent_client.py: HTTP client for agents
- utils/trilateration.py: Multi-agent position calculation
- static/js/core/agents.js: Frontend agent management
- templates/agents.html: Agent management page
- docs/DISTRIBUTED_AGENTS.md: System documentation

Modified:
- app.py: Register controller blueprint
- utils/database.py: Add agents and push_payloads tables
- templates/index.html: Add agent selector section

app.py

@@ -203,9 +203,14 @@ cleanup_manager.register(dsc_messages)
 # ============================================
 
 @app.before_request
-def require_login():
-    # Routes that don't require login (to avoid infinite redirect loop)
-    allowed_routes = ['login', 'static', 'favicon', 'health', 'health_check']
+def require_login():
+    # Routes that don't require login (to avoid infinite redirect loop)
+    allowed_routes = ['login', 'static', 'favicon', 'health', 'health_check']
+
+    # Controller API endpoints use API key auth, not session auth
+    # Allow agent push/pull endpoints without session login
+    if request.path.startswith('/controller/'):
+        return None  # Skip session check, controller routes handle their own auth
 
     # If user is not logged in and the current route is not allowed...
     if 'logged_in' not in session and request.endpoint not in allowed_routes:
@@ -710,4 +715,4 @@ def main() -> None:
         debug=args.debug,
         threaded=True,
         load_dotenv=False,
-    )
+    )