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/AIWeeklyDigest.swift

@@ -0,0 +1,64 @@
+//
+//  AIWeeklyDigest.swift
+//  Reflect
+//
+//  @Generable model and storage for AI-generated weekly emotional digest.
+//
+
+import Foundation
+import FoundationModels
+
+/// AI-generated weekly mood digest
+@available(iOS 26, *)
+@Generable
+struct AIWeeklyDigestResponse: Equatable {
+    @Guide(description: "An engaging headline summarizing the week's emotional arc (3-7 words)")
+    var headline: String
+
+    @Guide(description: "A warm 2-3 sentence summary of the week's mood patterns and notable moments")
+    var summary: String
+
+    @Guide(description: "The best moment or strongest positive pattern from the week (1 sentence)")
+    var highlight: String
+
+    @Guide(description: "A gentle, actionable intention or suggestion for the coming week (1 sentence)")
+    var intention: String
+
+    @Guide(description: "SF Symbol name for the digest icon (e.g., sun.max.fill, leaf.fill, heart.fill)")
+    var iconName: String
+}
+
+/// Storable weekly digest (Codable for UserDefaults persistence)
+struct WeeklyDigest: Codable, Equatable {
+    let headline: String
+    let summary: String
+    let highlight: String
+    let intention: String
+    let iconName: String
+    let generatedAt: Date
+    let weekStartDate: Date
+    let weekEndDate: Date
+
+    var isFromCurrentWeek: Bool {
+        let calendar = Calendar.current
+        let now = Date()
+        let currentWeekStart = calendar.dateInterval(of: .weekOfYear, for: now)?.start ?? now
+        let digestWeekStart = calendar.dateInterval(of: .weekOfYear, for: weekStartDate)?.start ?? weekStartDate
+        return calendar.isDate(currentWeekStart, inSameDayAs: digestWeekStart) ||
+               calendar.isDate(digestWeekStart, inSameDayAs: calendar.date(byAdding: .weekOfYear, value: -1, to: currentWeekStart)!)
+    }
+
+    /// Whether the digest was dismissed by the user
+    static var isDismissedKey: String { "weeklyDigestDismissedDate" }
+
+    static func markDismissed() {
+        GroupUserDefaults.groupDefaults.set(Date(), forKey: isDismissedKey)
+    }
+
+    static func isDismissed(for digest: WeeklyDigest) -> Bool {
+        guard let dismissedDate = GroupUserDefaults.groupDefaults.object(forKey: isDismissedKey) as? Date else {
+            return false
+        }
+        return dismissedDate >= digest.generatedAt
+    }
+}