T07b: frontend feature pages — companies + contacts + settings + audit + dashboard + search

- 11 new feature pages (CompaniesList/Detail/Form, ContactsList/Detail/Form,
  SettingsProfile/Roles/Users, AuditLog, GlobalSearchResults)
- 3 page updates (Dashboard with StatCard+ActivityFeed, Settings with tree nav+Outlet,
  TopBar with SearchDropdown)
- 13 new routes in routes/index.tsx
- i18n updates (de.json + en.json) with companies/contacts/settings/audit/search keys
- 12 new test files + 2 existing test fixes (TopBar, AppShell)
- 7 shared components (DataGrid, Tabs, SearchDropdown, CsvImportDialog, StatCard,
  ActivityFeed, UnsavedChangesGuard)
- 16 new API hooks in hooks.ts
- Verification: 141 tests pass, build succeeds, tsc --noEmit clean

frontend/src/i18n/locales/en.json

@@ -59,7 +59,87 @@
     "warning": "Warning",
     "info": "Information",
     "required": "Required",
-    "optional": "Optional"
+    "optional": "Optional",
+    "back": "Back",
+    "filter": "Filter",
+    "reset": "Reset",
+    "export": "Export",
+    "import": "Import",
+    "name": "Name",
+    "email": "Email",
+    "phone": "Phone",
+    "status": "Status",
+    "role": "Role",
+    "active": "Active",
+    "inactive": "Inactive"
+  },
+  "dashboard": {
+    "welcome": "Welcome back",
+    "recentActivity": "Recent Activity",
+    "statCompanies": "Companies",
+    "statContacts": "Contacts",
+    "statTasks": "Open Tasks",
+    "statEmails": "Emails Today"
+  },
+  "companies": {
+    "title": "Companies",
+    "create": "Create Company",
+    "edit": "Edit Company",
+    "name": "Company Name",
+    "accountNumber": "Account Number",
+    "industry": "Industry",
+    "phone": "Phone",
+    "email": "Email",
+    "website": "Website",
+    "description": "Description",
+    "contacts": "Contacts",
+    "files": "Files",
+    "activity": "Activity",
+    "overview": "Overview",
+    "export": "Export CSV",
+    "import": "Import CSV",
+    "deleteConfirm": "Are you sure you want to delete this company?",
+    "deleteConfirmTitle": "Delete Company",
+    "emptyTitle": "No companies yet",
+    "emptyDescription": "Create your first company to get started.",
+    "created": "Company created successfully.",
+    "updated": "Company updated successfully.",
+    "deleted": "Company deleted successfully.",
+    "createFailed": "Failed to create company.",
+    "updateFailed": "Failed to update company.",
+    "notFound": "Company not found.",
+    "noContacts": "This company has no contacts yet.",
+    "noFiles": "No files available.",
+    "noActivity": "No activity available."
+  },
+  "contacts": {
+    "title": "Contacts",
+    "create": "Create Contact",
+    "edit": "Edit Contact",
+    "firstName": "First Name",
+    "lastName": "Last Name",
+    "email": "Email",
+    "phone": "Phone",
+    "position": "Position",
+    "companies": "Companies",
+    "files": "Files",
+    "activity": "Activity",
+    "overview": "Overview",
+    "deleteConfirm": "Are you sure you want to delete this contact?",
+    "deleteConfirmTitle": "Delete Contact",
+    "emptyTitle": "No contacts yet",
+    "emptyDescription": "Create your first contact to get started.",
+    "created": "Contact created successfully.",
+    "updated": "Contact updated successfully.",
+    "deleted": "Contact deleted successfully.",
+    "createFailed": "Failed to create contact.",
+    "updateFailed": "Failed to update contact.",
+    "notFound": "Contact not found.",
+    "assignCompanies": "Assign Companies",
+    "noCompanies": "This contact is not assigned to any company.",
+    "noFiles": "No files available.",
+    "noActivity": "No activity available.",
+    "fullName": "Name"
   },
   "settings": {
     "title": "Settings",
@@ -70,7 +150,63 @@
     "system": "System",
     "profile": "Profile",
     "notifications": "Notifications",
-    "security": "Security"
+    "security": "Security",
+    "roles": "Roles",
+    "users": "Users",
+    "system": "System",
+    "name": "Name",
+    "firstName": "First Name",
+    "lastName": "Last Name",
+    "email": "Email",
+    "avatar": "Avatar",
+    "currentPassword": "Current Password",
+    "newPassword": "New Password",
+    "confirmPassword": "Confirm Password",
+    "changePassword": "Change Password",
+    "profileSaved": "Profile saved successfully.",
+    "passwordChanged": "Password changed successfully.",
+    "roleName": "Role Name",
+    "permissions": "Permissions",
+    "createRole": "Create Role",
+    "roleCreated": "Role created successfully.",
+    "roleUpdated": "Role updated successfully.",
+    "noRoles": "No roles available.",
+    "inviteUser": "Invite User",
+    "deactivate": "Deactivate",
+    "activate": "Activate",
+    "userInvited": "User invited successfully.",
+    "userDeactivated": "User deactivated.",
+    "userActivated": "User activated.",
+    "noUsers": "No users available.",
+    "assignRole": "Assign Role",
+    "inviteEmail": "Email Address",
+    "inviteRole": "Role"
+  },
+  "auditLog": {
+    "title": "Audit Log",
+    "user": "User",
+    "action": "Action",
+    "entity": "Entity",
+    "dateFrom": "Date From",
+    "dateTo": "Date To",
+    "details": "Details",
+    "timestamp": "Timestamp",
+    "empty": "No audit log entries available.",
+    "notAvailable": "Audit log is currently not available.",
+    "entityId": "Entity ID"
+  },
+  "search": {
+    "title": "Search Results",
+    "filters": "Filters",
+    "entityType": "Entity Type",
+    "allTypes": "All Types",
+    "companies": "Companies",
+    "contacts": "Contacts",
+    "noResults": "No results found for \"{{query}}\".",
+    "resultsFor": "Results for \"{{query}}\"",
+    "dateFrom": "Date From",
+    "dateTo": "Date To",
+    "enterQuery": "Enter a search term."
   },
   "topbar": {
     "tenant": "Tenant",
@@ -120,6 +256,7 @@
     "required": "This field is required.",
     "email": "Please enter a valid email address.",
     "minLength": "At least {{count}} characters required.",
-    "maxLength": "At most {{count}} characters allowed."
+    "maxLength": "At most {{count}} characters allowed.",
+    "passwordMismatch": "Passwords do not match."
   }
 }