feat: enhance database transactions, add Makefiles, and improve Docker setup

- Refactored database batch operations to ensure transaction atomicity and simplify nested structure.
- Added `Makefile` for `knowledge-base` and `llm-gateway` modules to streamline development workflows.
- Simplified `Dockerfile` for `llm-gateway` by removing multi-stage builds and optimizing dependencies.
- Improved code readability in `collection_manager` and `failover` modules with refined logic.
- Minor fixes in `test_server` and Redis health check handling for better diagnostics.

mcp-servers/llm-gateway/failover.py

@@ -110,14 +110,13 @@ class CircuitBreaker:
         """
         if self._state == CircuitState.OPEN:
             time_in_open = time.time() - self._stats.state_changed_at
-            if time_in_open >= self.recovery_timeout:
-                # Only transition if still in OPEN state (double-check)
-                if self._state == CircuitState.OPEN:
-                    self._transition_to(CircuitState.HALF_OPEN)
-                    logger.info(
-                        f"Circuit {self.name} transitioned to HALF_OPEN "
-                        f"after {time_in_open:.1f}s"
-                    )
+            # Double-check state after time calculation (for thread safety)
+            if time_in_open >= self.recovery_timeout and self._state == CircuitState.OPEN:
+                self._transition_to(CircuitState.HALF_OPEN)
+                logger.info(
+                    f"Circuit {self.name} transitioned to HALF_OPEN "
+                    f"after {time_in_open:.1f}s"
+                )
 
     def _transition_to(self, new_state: CircuitState) -> None:
         """Transition to a new state."""