Chore: clean up staged changes for release

- Remove standalone pulse-assistant architecture doc (content lives in CLAUDE.md)
- Add CountdownTimer component for patrol schedule display
- Rewrite patrol handler test to focus on interval persistence
- Extract MockStateProvider to shared test file

internal/api/mock_state_provider_test.go

@@ -0,0 +1,14 @@
+package api
+
+import (
+	"github.com/rcourtman/pulse-go-rewrite/internal/models"
+)
+
+// MockStateProvider is a mock implementation of ai.StateProvider for API tests
+type MockStateProvider struct {
+	State models.StateSnapshot
+}
+
+func (m *MockStateProvider) GetState() models.StateSnapshot {
+	return m.State
+}