fix(tags): Resolve critical tag deletion and migration notice bugs

Major Issues Fixed:

1. Tag Deletion Bug: Fixed critical issue where creating subtasks would delete other tags

   - Root cause: writeJSON function wasn't accepting projectRoot/tag parameters

   - Fixed writeJSON signature and logic to handle tagged data structure

   - Added proper merging of resolved tag data back into full tagged structure

2. Persistent Migration Notice: Fixed FYI notice showing after every command

   - Root cause: markMigrationForNotice was resetting migrationNoticeShown to false

   - Fixed migration logic to only trigger on actual legacy->tagged migrations

   - Added proper _rawTaggedData checks to prevent false migration detection

3. Data Corruption Prevention: Enhanced data integrity safeguards

   - Fixed writeJSON to filter out internal properties

   - Added automatic cleanup of rogue properties

   - Improved hasTaggedStructure detection logic

Commands Fixed: add-subtask, remove-subtask, and all commands now preserve tags correctly

scripts/modules/task-manager/add-task.js

@@ -226,12 +226,18 @@ async function addTask(
 		}
 
 		// Handle legacy format migration using utilities
-		if (rawData && Array.isArray(rawData.tasks)) {
-			report('Migrating legacy tasks.json format to tagged format...', 'info');
-			const legacyTasks = rawData.tasks;
+		if (rawData && Array.isArray(rawData.tasks) && !rawData._rawTaggedData) {
+			report('Legacy format detected. Migrating to tagged format...', 'info');
+
+			// This is legacy format - migrate it to tagged format
 			rawData = {
 				master: {
-					tasks: legacyTasks
+					tasks: rawData.tasks,
+					metadata: rawData.metadata || {
+						created: new Date().toISOString(),
+						updated: new Date().toISOString(),
+						description: 'Tasks for master context'
+					}
 				}
 			};
 			// Ensure proper metadata using utility