feat(tags): Add --tag flag support to core commands for multi-context task management

- parse-prd now supports creating tasks in specific contexts
- Fixed tag preservation logic to prevent data loss
- analyze-complexity generates tag-specific reports
- Non-existent tags created automatically
- Enables rapid prototyping and parallel development workflows

.taskmaster/state.json

@@ -1,6 +1,6 @@
 {
-  "currentTag": "master",
-  "lastSwitched": "2025-06-13T04:31:45.652Z",
+  "currentTag": "test-prd-tag",
+  "lastSwitched": "2025-06-13T06:07:05.204Z",
   "branchTagMapping": {},
   "migrationNoticeShown": true
 }