Feature: Add Settings page with centralized AI model configuration

- Add Settings page for AI model selection with load status indicators
- Add ModelWarmupService to preload configured model on app startup
- Consolidate AI model config to single AI:ReceiptParsingModel setting
- Simplify ViewReceipt and AICategorizePreview to use Settings model
- Improve AI categorization confidence prompt for varied scores

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

MoneyMap/Pages/ViewReceipt.cshtml.cs

@@ -4,8 +4,6 @@ using Microsoft.EntityFrameworkCore;
 using MoneyMap.Data;
 using MoneyMap.Models;
 using MoneyMap.Services;
-using System.Text.Json;
-using System.Text.Json.Nodes;
 
 namespace MoneyMap.Pages
 {
@@ -14,31 +12,24 @@ namespace MoneyMap.Pages
         private readonly MoneyMapContext _db;
         private readonly IReceiptManager _receiptManager;
         private readonly IEnumerable<IReceiptParser> _parsers;
-        private readonly LlamaCppVisionClient _llamaClient;
         private readonly IConfiguration _config;
-        private readonly IWebHostEnvironment _env;
 
         public ViewReceiptModel(
             MoneyMapContext db,
             IReceiptManager receiptManager,
             IEnumerable<IReceiptParser> parsers,
-            LlamaCppVisionClient llamaClient,
-            IConfiguration config,
-            IWebHostEnvironment env)
+            IConfiguration config)
         {
             _db = db;
             _receiptManager = receiptManager;
             _parsers = parsers;
-            _llamaClient = llamaClient;
             _config = config;
-            _env = env;
         }
 
         public Receipt? Receipt { get; set; }
         public List<ReceiptLineItem> LineItems { get; set; } = new();
         public List<ReceiptParseLog> ParseLogs { get; set; } = new();
         public List<ParserOption> AvailableParsers { get; set; } = new();
-        public List<LlamaCppModel> AvailableModels { get; set; } = new();
         public string ReceiptUrl { get; set; } = "";
         public string SelectedModel => _config["AI:ReceiptParsingModel"] ?? "gpt-4o-mini";
 
@@ -72,9 +63,6 @@ namespace MoneyMap.Pages
                 FullName = p.GetType().Name
             }).ToList();
 
-            // Get available LlamaCpp models
-            AvailableModels = await _llamaClient.GetAvailableModelsAsync();
-
             return Page();
         }
 
@@ -100,7 +88,7 @@ namespace MoneyMap.Pages
             return File(fileBytes, receipt.ContentType);
         }
 
-        public async Task<IActionResult> OnPostParseAsync(long id, string parser, string? model = null)
+        public async Task<IActionResult> OnPostParseAsync(long id, string parser)
         {
             var selectedParser = _parsers.FirstOrDefault(p => p.GetType().Name == parser);
 
@@ -110,13 +98,8 @@ namespace MoneyMap.Pages
                 return RedirectToPage(new { id });
             }
 
-            // Save selected model to config if it changed
-            if (!string.IsNullOrEmpty(model) && model != SelectedModel)
-            {
-                await SaveSelectedModelAsync(model);
-            }
-
-            var result = await selectedParser.ParseReceiptAsync(id, model);
+            // Use the configured model from settings
+            var result = await selectedParser.ParseReceiptAsync(id, SelectedModel);
 
             if (result.IsSuccess)
             {
@@ -130,33 +113,6 @@ namespace MoneyMap.Pages
             return RedirectToPage(new { id });
         }
 
-        private async Task SaveSelectedModelAsync(string model)
-        {
-            try
-            {
-                var appSettingsPath = Path.Combine(_env.ContentRootPath, "appsettings.json");
-                var json = await System.IO.File.ReadAllTextAsync(appSettingsPath);
-                var jsonNode = JsonNode.Parse(json);
-
-                if (jsonNode == null) return;
-
-                // Ensure AI section exists
-                if (jsonNode["AI"] == null)
-                {
-                    jsonNode["AI"] = new JsonObject();
-                }
-
-                jsonNode["AI"]!["ReceiptParsingModel"] = model;
-
-                var options = new JsonSerializerOptions { WriteIndented = true };
-                await System.IO.File.WriteAllTextAsync(appSettingsPath, jsonNode.ToJsonString(options));
-            }
-            catch
-            {
-                // Silently fail - not critical if we can't save the preference
-            }
-        }
-
         public class ParserOption
         {
             public string Name { get; set; } = "";