Complete IPC reconnection system with comprehensive error handling

- Resolve async cycle issues with boxed future hack for response_reader_task
- Enable reader task 'parting gift' reconnection for immediate recovery
- Simplify clear_connection_and_reconnect to return () with internal error handling
- Document write failure race condition edge case with rationale for acceptance
- Add comprehensive comments explaining concurrency model and recovery mechanisms

Architecture now provides multiple recovery points:
1. Reader task parting gift (immediate background reconnection)
2. Every MCP operation calls ensure_connection() (safety net)
3. Exponential backoff handles extension restart timing

Status: Complete reconnection system ready for integration testing

Author: nikomatsakis

server/Cargo.toml

@@ -28,6 +28,9 @@ schemars = { workspace = true }
 # Async runtime
 tokio = { workspace = true }
 
+# Async utilities
+futures = "0.3"
+
 # UUID generation for IPC message tracking
 uuid = { workspace = true }