Phase 4: Past appointments + AI prediction demo data

- Appointments: add ~25 past appointments (last 90 days) with Completed,
  Cancelled, No Show, and Rescheduled statuses; completed records carry
  ActualStartTime/ActualEndTime with realistic variance; cancel/no-show
  notes explain why; customer label falls back to ContactFirst/LastName
  for residential customers
- Fix future appointment title for residential customers (was always using
  CompanyName which is null for individuals)
- New SeedDataService.AiPredictions.cs: seeds 8 AiItemPrediction records
  (varied complexity/confidence/tags/reasoning) and attaches them to the
  first 8 eligible QuoteItems, marking those items IsAiItem=true; 3 of 8
  have UserOverrodeEstimate=true for AI Accuracy report demo
- SeedDataService.cs: wire SeedAiPredictionsAsync after Invoices
- Remove.cs: collect QuoteItem.AiPredictionId FKs before deleting items,
  then delete orphaned AiItemPrediction records after quotes are removed

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Infrastructure/Services/SeedDataService.Remove.cs

@@ -180,6 +180,14 @@ public partial class SeedDataService
 
                     if (seededQuoteIds.Any())
                     {
+                        // Collect prediction IDs before removing items (FK is NoAction — predictions
+                        // must be deleted after the items that reference them are gone).
+                        var predictionIds = await _context.QuoteItems.IgnoreQueryFilters()
+                            .Where(qi => seededQuoteIds.Contains(qi.QuoteId) && qi.AiPredictionId != null)
+                            .Select(qi => qi.AiPredictionId!.Value)
+                            .Distinct()
+                            .ToListAsync();
+
                         var quoteItems = await _context.QuoteItems.IgnoreQueryFilters()
                             .Where(qi => seededQuoteIds.Contains(qi.QuoteId)).ToListAsync();
                         if (quoteItems.Any()) _context.QuoteItems.RemoveRange(quoteItems);
@@ -193,6 +201,21 @@ public partial class SeedDataService
                         _context.Quotes.RemoveRange(quotes);
                         totalRemoved += quotes.Count;
                         details.Add($"✓ Removed {quotes.Count} seeded quote(s)");
+
+                        // Remove orphaned AI predictions now that QuoteItems no longer reference them
+                        if (predictionIds.Any())
+                        {
+                            var predictions = await _context.Set<Core.Entities.AiItemPrediction>()
+                                .IgnoreQueryFilters()
+                                .Where(p => predictionIds.Contains(p.Id))
+                                .ToListAsync();
+                            if (predictions.Any())
+                            {
+                                _context.Set<Core.Entities.AiItemPrediction>().RemoveRange(predictions);
+                                totalRemoved += predictions.Count;
+                                details.Add($"✓ Removed {predictions.Count} AI prediction(s)");
+                            }
+                        }
                     }
 
                     // Customer notes