Fix console logging and message routing

Console Logging Improvements:
- Changed ConsoleRuntimeProvider to send logs immediately instead of batching
- Track pending send promises and await them in onCompleted callback
- Ensures REPL gets all logs before execution-complete
- Enables real-time console logging for HTML artifacts

Message Routing Fixes:
- Remove "handled" concept from message routing - broadcast all messages to all providers/consumers
- Change handleMessage return type from Promise<boolean> to Promise<void>
- Add debug logging to RuntimeMessageRouter to trace message flow
- Fix duplicate error logging (window error handler now only tracks errors, doesn't log them)

Output Formatting Consistency:
- Remove [LOG], [ERROR] prefixes from console output in both tools
- Show console logs before error messages
- Use "=> value" format for return values in both javascript-repl and browser-javascript
- Remove duplicate "Error:" prefix and extra formatting

Bug Fixes:
- Fix race condition where execution-complete arrived before console logs
- Fix ConsoleRuntimeProvider blocking execution-complete from reaching consumers
- Remove duplicate console log collection from SandboxedIframe
- Fix return value capture by wrapping user code in async function

packages/web-ui/src/components/sandbox/FileDownloadRuntimeProvider.ts

@@ -77,20 +77,17 @@ export class FileDownloadRuntimeProvider implements SandboxRuntimeProvider {
 		};
 	}
 
-	async handleMessage(message: any, respond: (response: any) => void): Promise<boolean> {
-		if (message.type !== "file-returned") {
-			return false;
+	async handleMessage(message: any, respond: (response: any) => void): Promise<void> {
+		if (message.type === "file-returned") {
+			// Collect file for caller
+			this.files.push({
+				fileName: message.fileName,
+				content: message.content,
+				mimeType: message.mimeType,
+			});
+
+			respond({ success: true });
 		}
-
-		// Collect file for caller
-		this.files.push({
-			fileName: message.fileName,
-			content: message.content,
-			mimeType: message.mimeType,
-		});
-
-		respond({ success: true });
-		return true;
 	}
 
 	/**