refactor: unify model download system across all model types

- Add download-related methods to baseModelApi.js for fetching versions, roots, folders, and downloading models
- Replace separate download managers with a unified DownloadManager.js supporting all model types
- Create a single download_modals.html template that adapts to model type (LoRA, checkpoint, etc.)
- Remove old download modals from lora_modals.html and checkpoint_modals.html
- Update apiConfig.js to include civitaiVersions endpoints for each model type
- Centralize event handler binding in DownloadManager.js (no more inline HTML handlers)
- Modal UI and logic now auto-adapt to the current model type, making future extension easier

static/js/loras.js

@@ -3,7 +3,6 @@ import { state } from './state/index.js';
 import { loadMoreLoras } from './api/loraApi.js';
 import { updateCardsForBulkMode } from './components/LoraCard.js';
 import { bulkManager } from './managers/BulkManager.js';
-import { DownloadManager } from './managers/DownloadManager.js';
 import { moveManager } from './managers/MoveManager.js';
 import { LoraContextMenu } from './components/ContextMenu/index.js';
 import { createPageControls } from './components/controls/index.js';
@@ -17,9 +16,6 @@ class LoraPageManager {
         state.bulkMode = false;
         state.selectedLoras = new Set();
         
-        // Initialize managers
-        this.downloadManager = new DownloadManager();
-        
         // Initialize page controls
         this.pageControls = createPageControls('loras');
         
@@ -39,7 +35,6 @@ class LoraPageManager {
         window.closeDeleteModal = closeDeleteModal;
         window.confirmExclude = confirmExclude;
         window.closeExcludeModal = closeExcludeModal;
-        window.downloadManager = this.downloadManager;
         window.moveManager = moveManager;
         
         // Bulk operations