chore(claude): add YouTrack command suite

Port create-defect, create-story, estimate-issues, fix-defect,
implement-feature and split-story commands, adapted for the Angular
frontend (npm build/test, prettier gates, NCWF routing).
implement-feature now walks subtasks, respects blocked-by, and reports
cross-project (NCS/NCI) tasks. Ignore .claude/worktrees.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -37,3 +37,7 @@ __screenshots__/
 # System files
 .DS_Store
 Thumbs.db
+
+# Claude Code
+/.claude/settings.local.json
+/.claude/worktrees/