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/Models/MoodEntryModel.swift

@@ -48,11 +48,28 @@ final class MoodEntryModel {
     // Guided Reflection
     var reflectionJSON: String?
 
+    // AI-extracted theme tags (JSON array of strings)
+    var tagsJSON: String?
+
     // Computed properties
     var mood: Mood {
         Mood(rawValue: moodValue) ?? .missing
     }
 
+    /// Decoded tags from tagsJSON, or empty array if none
+    var tags: [String] {
+        guard let json = tagsJSON, let data = json.data(using: .utf8),
+              let decoded = try? JSONDecoder().decode([String].self, from: data) else {
+            return []
+        }
+        return decoded
+    }
+
+    /// Whether this entry has AI-extracted tags
+    var hasTags: Bool {
+        !tags.isEmpty
+    }
+
     var moodString: String {
         mood.strValue
     }