feat: implement Files page with persistent storage and version tracking

Three-panel file manager (nav, list, details) modeled after Stirling-PDF.
- Backend: user_files table, /api/v1/files/* CRUD routes, file storage
  helpers, thumbnail generation via Sharp, recursive CTE version chains
- Frontend: FilesNav, FileList, FileDetails, FileUploadArea components,
  Zustand store, mobile layout with bottom sheet
- Integration: tool-factory auto-saves results as new versions when
  fileId is provided, "Open File" loads file into tool processing flow
- Search, bulk select/delete/download, version badges, tool chain tags

apps/web/src/stores/file-store.ts

@@ -87,8 +87,7 @@ function deriveCompat(entries: FileEntry[], selectedIndex: number) {
     files: entries.map((e) => e.file),
     currentEntry: entry,
     hasFiles: entries.length > 0,
-    allProcessed:
-      entries.length > 0 && entries.every((e) => e.status === "completed"),
+    allProcessed: entries.length > 0 && entries.every((e) => e.status === "completed"),
     selectedFileName: entry ? entry.file.name : null,
     selectedFileSize: entry ? entry.file.size : null,
     originalBlobUrl: entry ? entry.blobUrl : null,
@@ -183,8 +182,7 @@ export const useFileStore = create<FileState>((set, get) => ({
     set({ entries, ...deriveCompat(entries, idx) });
   },
 
-  setBatchZip: (blob, filename) =>
-    set({ batchZipBlob: blob, batchZipFilename: filename }),
+  setBatchZip: (blob, filename) => set({ batchZipBlob: blob, batchZipFilename: filename }),
 
   setProcessing: (v) => set({ processing: v }),
 

apps/web/src/stores/files-page-store.ts

@@ -1,10 +1,5 @@
 import { create } from "zustand";
-import {
-  apiListFiles,
-  apiUploadUserFiles,
-  apiDeleteUserFiles,
-  type UserFile,
-} from "@/lib/api";
+import { apiDeleteUserFiles, apiListFiles, apiUploadUserFiles, type UserFile } from "@/lib/api";
 
 interface FilesPageState {
   files: UserFile[];
@@ -75,12 +70,15 @@ export const useFilesPageStore = create<FilesPageState>((set, get) => ({
   toggleChecked: (id) => {
     const { checkedIds } = get();
     const next = new Set(checkedIds);
-    if (next.has(id)) next.delete(id); else next.add(id);
+    if (next.has(id)) next.delete(id);
+    else next.add(id);
     set({ checkedIds: next });
   },
   toggleCheckAll: () => {
     const { files, checkedIds } = get();
-    set({ checkedIds: checkedIds.size === files.length ? new Set() : new Set(files.map(f => f.id)) });
+    set({
+      checkedIds: checkedIds.size === files.length ? new Set() : new Set(files.map((f) => f.id)),
+    });
   },
   setSearchQuery: (q) => set({ searchQuery: q }),
   setActiveTab: (tab) => set({ activeTab: tab }),