♻️ refactor: On-demand MCP connections: remove proactive reconnect, default to available (#11839)

* feat: Implement reconnection staggering and backoff jitter for MCP connections

- Enhanced the reconnection logic in OAuthReconnectionManager to stagger reconnection attempts for multiple servers, reducing the risk of connection storms.
- Introduced a backoff delay with random jitter in MCPConnection to improve reconnection behavior during network issues.
- Updated the ConnectionsRepository to handle multiple server connections concurrently with a defined concurrency limit.

Added tests to ensure the new reconnection strategy works as intended.

* refactor: Update MCP server query configuration for improved data freshness

- Reduced stale time from 5 minutes to 30 seconds to ensure quicker updates on server initialization.
- Enabled refetching on window focus and mount to enhance data accuracy during user interactions.

* ♻️  refactor: On-demand MCP connections; remove proactive reconnection, default to available

  - Remove reconnectServers() from refresh controller (connection storm root cause)
  - Stop gating server selection on connection status; add to selection immediately
  - Render agent panel tools from DB cache, not live connection status
  - Proceed to cached tools on init failure (only gate on OAuth)
  - Remove unused batchToggleServers()
  - Reduce useMCPServersQuery staleTime from 5min to 30s, enable refetchOnMount/WindowFocus

* refactor: Optimize MCP tool initialization and server connection logic

- Adjusted tool initialization to only occur if no cached tools are available, improving efficiency.
- Updated comments for clarity on server connection and tool fetching processes.
- Removed unnecessary connection status checks during server selection to streamline the user experience.

client/src/data-provider/MCP/queries.ts

@@ -12,10 +12,10 @@ export const useMCPServersQuery = <TData = t.MCPServersListResponse>(
     [QueryKeys.mcpServers],
     () => dataService.getMCPServers(),
     {
-      staleTime: 1000 * 60 * 5, // 5 minutes - data stays fresh longer
-      refetchOnWindowFocus: false,
+      staleTime: 30 * 1000, // 30 seconds — short enough to pick up servers that finish initializing after first load
+      refetchOnWindowFocus: true,
       refetchOnReconnect: false,
-      refetchOnMount: false,
+      refetchOnMount: true,
       retry: false,
       ...config,
     },