fix: remove -x from coverage pytest to prevent suite-blocking failures (#1360)

One flaky test (test_builtin_echo_tool timeout) was stopping the entire
e2e coverage suite via -x, preventing 118+ remaining tests from running
and generating coverage data.

Tests are independent (each gets a fresh browser context via the
function-scoped page fixture), so removing -x is safe.

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

Author: henrypark133

.github/workflows/coverage.yml

@@ -174,7 +174,7 @@ jobs:
 
       - name: Run E2E tests
         run: |
-          pytest tests/e2e/ -v -x --timeout=120
+          pytest tests/e2e/ -v --timeout=120
         env:
           RUST_LOG: ironclaw=info
           RUST_BACKTRACE: "1"