feat: Dynamic base model fetching from Civitai API (#854)

Implement automatic fetching of base models from Civitai API to keep
data up-to-date without manual updates.

Backend:
- Add CivitaiBaseModelService with 7-day TTL caching
- Add /api/lm/base-models endpoints for fetching and refreshing
- Merge hardcoded and remote models for backward compatibility
- Smart abbreviation generation for unknown models

Frontend:
- Add civitaiBaseModelApi client for API communication
- Dynamic base model loading on app initialization
- Update SettingsManager to use merged model lists
- Add support for 8 new models: Anima, CogVideoX, LTXV 2.3, Mochi,
  Pony V7, Wan Video 2.5 T2V/I2V

API Endpoints:
- GET /api/lm/base-models - Get merged models
- POST /api/lm/base-models/refresh - Force refresh
- GET /api/lm/base-models/categories - Get categories
- GET /api/lm/base-models/cache-status - Check cache status

Closes #854

static/js/core.js

@@ -17,6 +17,8 @@ import { onboardingManager } from './managers/OnboardingManager.js';
 import { BulkContextMenu } from './components/ContextMenu/BulkContextMenu.js';
 import { createPageContextMenu, createGlobalContextMenu } from './components/ContextMenu/index.js';
 import { initializeEventManagement } from './utils/eventManagementInit.js';
+import { civitaiBaseModelApi } from './api/civitaiBaseModelApi.js';
+import { setDynamicBaseModels } from './utils/constants.js';
 
 // Core application class
 export class AppCore {
@@ -42,6 +44,10 @@ export class AppCore {
         await settingsManager.waitForInitialization();
         console.log('AppCore: Settings initialized');
         
+        // Initialize dynamic base models (async, non-blocking)
+        console.log('AppCore: Initializing dynamic base models...');
+        this.initializeDynamicBaseModels();
+        
         // Initialize managers
         state.loadingManager = new LoadingManager();
         modalManager.initialize();
@@ -116,6 +122,21 @@ export class AppCore {
             window.globalContextMenuInstance = createGlobalContextMenu();
         }
     }
+    
+    // Initialize dynamic base models from Civitai API
+    // This is non-blocking - runs in background
+    async initializeDynamicBaseModels() {
+        try {
+            const result = await civitaiBaseModelApi.getBaseModels();
+            if (result && result.models) {
+                setDynamicBaseModels(result.models, result.last_updated);
+                console.log(`AppCore: Loaded ${result.merged_count} base models (${result.hardcoded_count} hardcoded + ${result.remote_count} remote)`);
+            }
+        } catch (error) {
+            console.warn('AppCore: Failed to load dynamic base models:', error);
+            // Non-critical error - app continues with hardcoded models
+        }
+    }
 }
 
 // Create and export a singleton instance