- Introduce `hostHTTPOperationBridge` to manage, claim, and cancel host HTTP operations with scoped cleanups
- Scope HTTP operations and streams to specific plugin instances to isolate lifecycles and prevent cross-plugin access
- Add RPC handlers for `MethodHostHTTPOperationOpen` and `MethodHostHTTPCancel`
- Link operation cancellation and resource cleanup to host callback contexts and stream termination
Closes: #6085