Replace TipKit with custom themed tips modal system

- Add TipModalView with gradient header, themed styling, and spring animations
- Create FeelsTipsManager with global toggle, session tracking, and persistence
- Define FeelsTip protocol and convert all 7 tips to new system
- Add convenience view modifiers (.customizeLayoutTip(), .aiInsightsTip(), etc.)
- Remove TipKit dependency from all views
- Add Tips Preview debug screen in Settings to test all tip modals
- Update documentation for new custom tips system

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Shared/MoodLogger.swift

@@ -82,10 +82,10 @@ final class MoodLogger {
         LiveActivityManager.shared.updateActivity(streak: streak, mood: mood)
         LiveActivityScheduler.shared.scheduleForNextDay()
 
-        // 4. Update TipKit parameters if requested
+        // 4. Update tips parameters if requested
         if updateTips {
-            TipsManager.shared.onMoodLogged()
-            TipsManager.shared.updateStreak(streak)
+            FeelsTipsManager.shared.onMoodLogged()
+            FeelsTipsManager.shared.updateStreak(streak)
         }
 
         // 5. Request app review at moments of delight