feat: Replace python tests with native E2E test suite and fix capabilities schema

- Added native E2E test suite in stub to validate server<->stub<->nvim IPC
- Added win-nvim integration tests
- Fixed empty capabilities schema in initialize response in server and win-nvim
- Refactored server to accept dynamic MCP_PORT for test isolation
- Made server exit gracefully on port 3000 collision

server/src/handlers.rs

@@ -26,7 +26,9 @@ impl MemoryHandler {
                     id,
                     serde_json::json!({
                         "protocolVersion": "2024-11-05",
-                        "capabilities": {},
+                        "capabilities": {
+                            "tools": {}
+                        },
                         "serverInfo": {
                             "name": "gemini-mcp-memory",
                             "version": "3.0.0"
@@ -1607,3 +1609,7 @@ crate::mcp::tool_def::<CreateEntitiesTool>("create_entities", "Create new entiti
         }
     }
 }
+
+
+
+