Add AI-powered mental wellness features: Reflection Companion, Pattern Tags, Weekly Digest

Three new Foundation Models features to deepen user engagement with mental wellness:

1. AI Reflection Companion — personalized feedback after completing guided reflections,
   referencing the user's actual words with personality-pack-adapted tone
2. Mood Pattern Tags — auto-extracts theme tags (work, family, stress, etc.) from notes
   and reflections, displayed as colored pills on entries
3. Weekly Emotional Digest — BGTask-scheduled Sunday digest with headline, summary,
   highlight, and intention; shown as card in Insights tab with notification

All features: on-device (zero cost), premium-gated, iOS 26+ with graceful degradation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Shared/Persisence/DataControllerUPDATE.swift

@@ -63,6 +63,16 @@ extension DataController {
         return true
     }
 
+    // MARK: - Tags
+
+    @discardableResult
+    func updateTags(forDate date: Date, tagsJSON: String?) -> Bool {
+        guard let entry = getEntry(byDate: date) else { return false }
+        entry.tagsJSON = tagsJSON
+        saveAndRunDataListeners()
+        return true
+    }
+
     // MARK: - Photo
 
     @discardableResult