fix: refactor tool execution to use generateText with proper tool handling

Major changes:
- Fixed package executor URL protocol handling (add https:// if missing)
- Switched from streamText to generateText for proper tool execution
- AI now calls tool AND generates natural language response
- Tool results no longer show raw JSON metadata

Tool executor (tool-executor-agent.ts):
- Use generateText() instead of streamText() for tool execution
- Add system prompt to guide AI to summarize tool results
- Return result.text for natural language output
- Tool definition uses inputSchema (AI SDK v6 format)

Package executor:
- Add getSandboxUrl() to ensure URL has https:// protocol
- Fixes "Failed to parse URL" error in production

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

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

packages/package-executor/src/executor.ts

@@ -6,7 +6,18 @@
 import type { ExecutionResult, ExecutorOptions } from './types.js';
 
 const DEFAULT_TIMEOUT = 10000; // 10 seconds
-const SANDBOX_URL = process.env.SANDBOX_EXECUTOR_URL || 'http://localhost:3000';
+
+// Ensure URL has protocol
+function getSandboxUrl(): string {
+  const url = process.env.SANDBOX_EXECUTOR_URL || 'http://localhost:3000';
+  // If URL doesn't start with http:// or https://, add https://
+  if (!url.startsWith('http://') && !url.startsWith('https://')) {
+    return `https://${url}`;
+  }
+  return url;
+}
+
+const SANDBOX_URL = getSandboxUrl();
 
 /**
  * Execute a package function with parameters via remote sandbox