Optimize AI generation speed and add richer insight data

Speed optimizations:
- Add session.prewarm() in InsightsViewModel and ReportsViewModel init
  for 40% faster first-token latency
- Cap maximumResponseTokens on all 8 AI respond() calls (100-600 per use case)
- Add prompt brevity constraints ("1-2 sentences", "2 sentences")
- Reduce report batch concurrency from 4 to 2 to prevent device contention
- Pre-fetch health data once and share across all 3 insight periods

Richer insight data in MoodDataSummarizer:
- Tag-mood correlations: overall frequency + good day vs bad day tag breakdown
- Weather-mood correlations: avg mood by condition and temperature range
- Absence pattern detection: logging gap count with pre/post-gap mood averages
- Entry source breakdown: % of entries from App, Widget, Watch, Siri, etc.
- Update insight prompt to leverage tags, weather, and gap data when available

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

Shared/Views/InsightsView/InsightsViewModel.swift

@@ -57,6 +57,7 @@ class InsightsViewModel: ObservableObject {
             let service = FoundationModelsInsightService()
             insightService = service
             isAIAvailable = service.isAvailable
+            service.prewarm()
         } else {
             insightService = nil
             isAIAvailable = false
@@ -118,12 +119,23 @@ class InsightsViewModel: ObservableObject {
         let yearEntries = DataController.shared.getData(startDate: yearStart, endDate: now, includedDays: [1, 2, 3, 4, 5, 6, 7])
         let allTimeEntries = DataController.shared.getData(startDate: allTimeStart, endDate: now, includedDays: [1, 2, 3, 4, 5, 6, 7])
 
+        // Pre-fetch health data once (instead of 3x per period)
+        var sharedHealthAverages: HealthService.HealthAverages?
+        if healthService.isEnabled && healthService.isAuthorized {
+            let allValidEntries = allTimeEntries.filter { ![.missing, .placeholder].contains($0.mood) }
+            if !allValidEntries.isEmpty {
+                let healthData = await healthService.fetchHealthData(for: allValidEntries)
+                sharedHealthAverages = healthService.computeHealthAverages(entries: allValidEntries, healthData: healthData)
+            }
+        }
+
         // Generate insights concurrently for all three periods
         await withTaskGroup(of: Void.self) { group in
             group.addTask { @MainActor in
                 await self.generatePeriodInsights(
                     entries: monthEntries,
                     periodName: "this month",
+                    healthAverages: sharedHealthAverages,
                     updateState: { self.monthLoadingState = $0 },
                     updateInsights: { self.monthInsights = $0 }
                 )
@@ -133,6 +145,7 @@ class InsightsViewModel: ObservableObject {
                 await self.generatePeriodInsights(
                     entries: yearEntries,
                     periodName: "this year",
+                    healthAverages: sharedHealthAverages,
                     updateState: { self.yearLoadingState = $0 },
                     updateInsights: { self.yearInsights = $0 }
                 )
@@ -142,6 +155,7 @@ class InsightsViewModel: ObservableObject {
                 await self.generatePeriodInsights(
                     entries: allTimeEntries,
                     periodName: "all time",
+                    healthAverages: sharedHealthAverages,
                     updateState: { self.allTimeLoadingState = $0 },
                     updateInsights: { self.allTimeInsights = $0 }
                 )
@@ -152,6 +166,7 @@ class InsightsViewModel: ObservableObject {
     private func generatePeriodInsights(
         entries: [MoodEntryModel],
         periodName: String,
+        healthAverages: HealthService.HealthAverages?,
         updateState: @escaping (InsightLoadingState) -> Void,
         updateInsights: @escaping ([Insight]) -> Void
     ) async {
@@ -184,13 +199,6 @@ class InsightsViewModel: ObservableObject {
 
         updateState(.loading)
 
-        // Fetch health data if enabled - pass raw averages to AI for correlation analysis
-        var healthAverages: HealthService.HealthAverages?
-        if healthService.isEnabled && healthService.isAuthorized {
-            let healthData = await healthService.fetchHealthData(for: validEntries)
-            healthAverages = healthService.computeHealthAverages(entries: validEntries, healthData: healthData)
-        }
-
         if #available(iOS 26, *), let service = insightService as? FoundationModelsInsightService {
             do {
                 let insights = try await service.generateInsights(