fix: resolve API inconsistencies found by Mokoto

- Bug 1: No fix needed - frontend already uses PUT for document updates
- Bug 2: Changed folders API to use 'project' param (matches documents)
- Bug 3: GET /folders now works without project filter (lists all folders)

Changes:
- folders.js: Accept 'project' instead of 'projectId', make it optional
- folderService.js: Support listing all folders when projectId is null
- api.js: Updated getFolders() to use 'project' param consistently

public/js/api.js

@@ -171,10 +171,12 @@ class ApiClient {
   }
 
   // ===== Folders =====
-  getFolders(projectId, parentId = null) {
-    const params = new URLSearchParams({ projectId });
+  getFolders(project = null, parentId = null) {
+    const params = new URLSearchParams();
+    if (project) params.append('project', project);
     if (parentId) params.append('parentId', parentId);
-    return this.get(`/folders?${params.toString()}`);
+    const query = params.toString();
+    return this.get(`/folders${query ? '?' + query : ''}`);
   }
 
   getFolder(id) {

src/routes/folders.js

@@ -11,15 +11,12 @@ import { NotFoundError, ValidationError } from '../utils/errors.js';
 const router = Router();
 router.use(authMiddleware);
 
-// GET /folders?projectId=X&parentId=Y - List folders
+// GET /folders?project=X&parentId=Y - List folders (project is optional, matches documents API)
 router.get('/', async (req, res) => {
   try {
-    const { projectId, parentId } = req.query;
-    if (!projectId) {
-      throw new ValidationError('projectId query parameter is required');
-    }
+    const { project, parentId } = req.query;
     const folderService = getFolderService();
-    const folders = await folderService.getFolders(projectId, parentId || null);
+    const folders = await folderService.getFolders(project || null, parentId || null);
     res.json({ folders });
   } catch (err) {
     if (err instanceof ValidationError) {

src/services/folderService.js

@@ -157,12 +157,14 @@ export class FolderService {
     }
   }
 
-  async getFolders(projectId, parentId = null) {
-    // Verify project exists
+  async getFolders(projectId = null, parentId = null) {
+    const folders = [];
+
+    // If projectId is provided, verify it exists
+    if (projectId) {
       const projectService = getProjectService(this.dataRoot);
       await projectService.getProject(projectId);
-
-    const folders = [];
+    }
 
     if (parentId) {
       // Get folders within a specific parent
@@ -187,8 +189,8 @@ export class FolderService {
           folderCount: this._countSubFolders(join(entryPath, 'sub-folders')),
         });
       }
-    } else {
-      // Get root folders of the project
+    } else if (projectId) {
+      // Get root folders of a specific project
       const rootFoldersPath = this._projectFoldersPath(projectId);
       if (!pathExists(rootFoldersPath)) {
         return folders;
@@ -208,6 +210,35 @@ export class FolderService {
           folderCount: this._countSubFolders(join(entryPath, 'sub-folders')),
         });
       }
+    } else {
+      // No projectId provided - list folders from all projects
+      if (!pathExists(this.projectsPath)) {
+        return folders;
+      }
+
+      const projectEntries = listDir(this.projectsPath);
+      for (const projectEntry of projectEntries) {
+        const projectPath = join(this.projectsPath, projectEntry);
+        if (!isDirectory(projectPath)) continue;
+
+        const rootFoldersPath = join(projectPath, FOLDERS_DIR);
+        if (!pathExists(rootFoldersPath)) continue;
+
+        const entries = listDir(rootFoldersPath);
+        for (const entry of entries) {
+          const entryPath = join(rootFoldersPath, entry);
+          if (!isDirectory(entryPath)) continue;
+
+          const meta = readJSON(join(entryPath, FOLDER_META_FILE));
+          if (!meta) continue;
+
+          folders.push({
+            ...meta,
+            documentCount: this._countDocuments(join(entryPath, 'documents')),
+            folderCount: this._countSubFolders(join(entryPath, 'sub-folders')),
+          });
+        }
+      }
     }
 
     return folders;