fix: client file sharing access denied + task/project default tabs

- FileSharing: rootPath for clients strips /Clients/ prefix — API resolveClientPath expects /{company} not /Clients/{company}
- Tasks: default to To Do tab (not_started) instead of All Tasks
- Projects: default to Active tab instead of All Projects

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/FileSharing.jsx

@@ -270,12 +270,16 @@ async function fbqProxy(op, path, extra = {}) {
   throw new Error(`Unsupported operation: ${op}`);
 }
 
+function safeName(v) {
+  return String(v || '').trim().replace(/[\\/:*?"<>|#%{}^~[\]`]+/g, '-').replace(/\s+/g, ' ').replace(/^-+|-+$/g, '');
+}
+
 function rootPath(user) {
   if (!user || user.role === 'team' || user.role === 'external') return '/';
   const companies = user.companies?.filter(Boolean) ?? [];
-  if (companies.length > 1) return '/Clients';
+  if (companies.length > 1) return '/';
   const name = companies[0]?.name ?? user.company?.name;
-  return name ? `/Clients/${name}` : '/';
+  return name ? `/${safeName(name)}` : '/';
 }
 
 function parsePath(path) {