fix(browser): auto-start CDP bridge on BrowserTool init

The CDP bridge server (ws://localhost:9223 + http://localhost:9224)
was never starting because the entrypoint loader instantiates
BrowserTool directly, bypassing the package-level register_tools()
which called start_cdp_bridge().

Now BrowserTool.__init__() auto-starts the bridge when backend is
not "playwright", ensuring the browser extension can connect and
be used as the preferred backend over headless Playwright.

pkg/hanzo-tools-browser/hanzo_tools/browser/browser_tool.py

@@ -672,6 +672,17 @@ class BrowserTool(BaseTool):
         self.backend = backend or get_backend()
         self.timeout = 30000
 
+        # Auto-start CDP bridge for browser extension integration.
+        # This enables the extension (Chrome/Firefox/Safari) to connect
+        # and be preferred over Playwright when backend != "playwright".
+        if self.backend != "playwright":
+            try:
+                from hanzo_tools.browser import start_cdp_bridge, CDP_BRIDGE_AVAILABLE
+                if CDP_BRIDGE_AVAILABLE:
+                    start_cdp_bridge()
+            except Exception:
+                pass
+
     @property
     def description(self) -> str:
         return """Complete browser automation with full Playwright API.