fix(extension): handle browser error pages gracefully

- Treat chrome error page script failures as transient during injection retries.
- Return safe fallback values for read-only DOM commands when tabs land on browser error pages.
- Improve URL watch handling by checking pending URLs and reporting last seen URL/status on timeout.
- Bump package and extension version to 0.9.6 and add regression coverage for error-page behavior.

tests/test_extension_error_page_handling.py

@@ -0,0 +1,28 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+
+def test_extension_retries_error_page_script_injection_before_failing():
+    core = (ROOT / "extension" / "src" / "core.ts").read_text()
+
+    assert "isErrorPageScriptError" in core
+    assert "chrome-error://chromewebdata" in core
+    assert "isTransientScriptError(e)" in core
+
+def test_read_only_dom_commands_have_error_page_fallbacks():
+    dom = (ROOT / "extension" / "src" / "commands" / "dom.ts").read_text()
+
+    assert "fallbackForErrorPageDomOp" in dom
+    assert 'case "domExists":' in dom
+    assert "return false;" in dom
+    assert 'case "domQuery":' in dom
+    assert 'case "extractText":' in dom
+    assert "isErrorPageScriptError(e)" in dom
+
+def test_tabs_watch_url_reports_last_seen_url_on_timeout():
+    tabs = (ROOT / "extension" / "src" / "commands" / "tabs.ts").read_text()
+
+    assert "lastUrl" in tabs
+    assert "lastStatus" in tabs
+    assert "showing an error page" in tabs
+    assert "last URL:" in tabs