Fix bug modelcontextprotocol#14 & modelcontextprotocol#15: Remove blocking logger calls from ProcessTransport stderr + Add 30s timeout to Client.send()

Bug modelcontextprotocol#14: ProcessTransport.logStderr() had 2 blocking logger calls
- logger.warning() and logger.error() cause actor isolation delays
- Replaced with NSLog for synchronous stderr logging

Bug modelcontextprotocol#15: Client.send() had no timeout mechanism
- Requests would hang indefinitely if MCP server didn't respond
- Added 30-second timeout using withThrowingTaskGroup
- Properly cleans up pending requests on timeout
- Logs timeout with clear error message

These fixes allow us to:
1. See stderr output from MCP servers without delays
2. Detect and recover from hung MCP server processes
3. Provide better error messages to users when tools fail

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dcherrera

Sources/MCP/Client/Client.swift

@@ -325,39 +325,62 @@ public actor Client {
         }
 
         let requestData = try encoder.encode(request)
-        NSLog("🔵 CLIENT.send() - Encoded request, entering continuation")
-
-        // Store the pending request first
-        return try await withCheckedThrowingContinuation { continuation in
-            NSLog("🔵 CLIENT.send() - Inside continuation, creating Task")
-            Task {
-                NSLog("🔵 CLIENT.send() - Task started, adding pending request")
-                // Add the pending request before attempting to send
-                self.addPendingRequest(
-                    id: request.id,
-                    continuation: continuation,
-                    type: M.Result.self
-                )
-                NSLog("🔵 CLIENT.send() - Pending request added, calling connection.send()")
-
-                // Send the request data
-                do {
-                    // Use the existing connection send
-                    try await connection.send(requestData)
-                    NSLog("🔵 CLIENT.send() - connection.send() succeeded")
-                } catch {
-                    NSLog("🔵 CLIENT.send() - connection.send() failed: \(error)")
-                    // If send fails, try to remove the pending request.
-                    // Resume with the send error only if we successfully removed the request,
-                    // indicating the response handler hasn't processed it yet.
-                    if self.removePendingRequest(id: request.id) != nil {
-                        continuation.resume(throwing: error)
+        NSLog("🔵 CLIENT.send() - Encoded request, adding timeout wrapper")
+
+        // Add timeout wrapper (30 seconds) to prevent infinite hangs
+        return try await withThrowingTaskGroup(of: M.Result.self) { group in
+            // Task 1: Actual send operation
+            group.addTask {
+                return try await withCheckedThrowingContinuation { continuation in
+                    NSLog("🔵 CLIENT.send() - Inside continuation, creating Task")
+                    Task {
+                        NSLog("🔵 CLIENT.send() - Task started, adding pending request")
+                        // Add the pending request before attempting to send
+                        self.addPendingRequest(
+                            id: request.id,
+                            continuation: continuation,
+                            type: M.Result.self
+                        )
+                        NSLog("🔵 CLIENT.send() - Pending request added, calling connection.send()")
+
+                        // Send the request data
+                        do {
+                            // Use the existing connection send
+                            try await connection.send(requestData)
+                            NSLog("🔵 CLIENT.send() - connection.send() succeeded, waiting for response...")
+                        } catch {
+                            NSLog("🔵 CLIENT.send() - connection.send() failed: \(error)")
+                            // If send fails, try to remove the pending request.
+                            // Resume with the send error only if we successfully removed the request,
+                            // indicating the response handler hasn't processed it yet.
+                            if self.removePendingRequest(id: request.id) != nil {
+                                continuation.resume(throwing: error)
+                            }
+                            // Otherwise, the request was already removed by the response handler
+                            // or by disconnect, so the continuation was already resumed.
+                            // Do nothing here.
+                        }
                     }
-                    // Otherwise, the request was already removed by the response handler
-                    // or by disconnect, so the continuation was already resumed.
-                    // Do nothing here.
                 }
             }
+
+            // Task 2: Timeout task (30 seconds)
+            group.addTask {
+                try await Task.sleep(nanoseconds: 30_000_000_000)
+                NSLog("⏰ CLIENT.send() - TIMEOUT after 30 seconds for method: \(M.name)")
+                throw MCPError.internalError("Request timed out after 30 seconds")
+            }
+
+            // Wait for first task to complete (either success or timeout)
+            do {
+                let result = try await group.next()!
+                group.cancelAll() // Cancel the other task
+                return result
+            } catch {
+                // Clean up pending request on timeout
+                _ = self.removePendingRequest(id: request.id)
+                throw error
+            }
         }
     }