Merge main into refactor/frontend

Merge latest features from main including:
- PR #161 (worktree-confusion): Clarified branch handling in dialogs
- PR #160 (speckits-rebase): Planning mode functionality

Resolved conflicts:
- add-feature-dialog.tsx: Combined TanStack Router navigation with branch selection state
- worktree-integration.spec.ts: Updated tests for new worktree behavior (created at execution time)
- package-lock.json: Regenerated after merge

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/ui/tests/utils/core/constants.ts

@@ -97,7 +97,7 @@ export const TEST_IDS = {
   addFeatureButton: "add-feature-button",
   addFeatureDialog: "add-feature-dialog",
   confirmAddFeature: "confirm-add-feature",
-  featureBranchInput: "feature-branch-input",
+  featureBranchInput: "feature-input",
   featureCategoryInput: "feature-category-input",
   worktreeSelector: "worktree-selector",