refactor(frontend): Consolidate credential API endpoints to /api/system/credentials

Simplified credential API usage by removing v2 endpoint confusion and
consolidating all credential operations to use /api/system/credentials.

Changes:
- Settings.tsx: Updated GET, POST, PUT, DELETE to use /api/system/credentials
- AddHost.tsx: Updated system credential fetching endpoint
- HostsEnhanced.tsx: Updated system credential fetching endpoint

Why:
- Application is in development/testing phase - no need for v1/v2 versioning
- Frontend was inconsistently using /api/v2/credentials and /api/system/credentials
- Backend already has unified implementation at /api/system/credentials
- Reduces confusion and maintenance overhead

Security:
- No changes to authentication/authorization logic
- All endpoints still require valid JWT tokens
- Credential encryption unchanged
- RBAC controls preserved

Testing: Manual verification needed via Settings UI

Related: System credentials migration from dual-table to unified_credentials

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: remyluslosius

frontend/src/pages/hosts/AddHost.tsx

@@ -307,8 +307,8 @@ const AddHost: React.FC = () => {
   // Fetch system default credentials for display
   const fetchSystemCredentials = async () => {
     try {
-      // WEEK 2 MIGRATION: Use v2 API with scope filter (trailing slash required)
-      const response = await fetch('/api/v2/credentials/?scope=system', {
+      // Use unified credentials API with scope filter
+      const response = await fetch('/api/system/credentials?scope=system', {
         headers: {
           'Authorization': `Bearer ${localStorage.getItem('auth_token')}`
         }

frontend/src/pages/hosts/HostsEnhanced.tsx

@@ -742,8 +742,8 @@ const HostsEnhanced: React.FC = () => {
 
   const fetchSystemCredentialsForEdit = async () => {
     try {
-      // WEEK 2 MIGRATION: Use v2 API with scope filter (trailing slash required)
-      const response = await api.get('/api/v2/credentials/?scope=system');
+      // Use unified credentials API with scope filter
+      const response = await api.get('/api/system/credentials?scope=system');
       const defaultCredential = response.find((cred: any) => cred.is_default);
 
       if (defaultCredential) {

frontend/src/pages/settings/Settings.tsx

@@ -178,12 +178,12 @@ const Settings: React.FC = () => {
 
     try {
       setLoading(true);
-      // WEEK 2 MIGRATION: Use v2 API with scope filter and inactive toggle
+      // Use unified credentials API with scope filter and inactive toggle
       const params = new URLSearchParams({
         scope: 'system',
         include_inactive: showInactive.toString()
       });
-      const response = await api.get(`/api/v2/credentials/?${params}`);
+      const response = await api.get(`/api/system/credentials?${params}`);
       setCredentials(response); // API directly returns array
     } catch (err: any) {
       setError('Failed to load system credentials');
@@ -343,8 +343,8 @@ const Settings: React.FC = () => {
     }
 
     try {
-      // WEEK 2 MIGRATION: Use v2 DELETE endpoint (trailing slash required)
-      await api.delete(`/api/v2/credentials/${id}/`);
+      // Use unified credentials API DELETE endpoint
+      await api.delete(`/api/system/credentials/${id}`);
       setSuccess('Credential set deleted successfully');
       loadCredentials();
     } catch (err: any) {
@@ -359,17 +359,17 @@ const Settings: React.FC = () => {
       setLoading(true);
 
       if (editingCredential) {
-        // Update existing credential (keep using v1 PUT - already on unified_credentials)
+        // Update existing credential using unified credentials API
         await api.put(`/api/system/credentials/${editingCredential.id}`, formData);
         setSuccess('Credential set updated successfully');
       } else {
-        // WEEK 2 MIGRATION: Create new credential using v2 API (trailing slash required)
-        const v2FormData = {
+        // Create new credential using unified credentials API
+        const createFormData = {
           ...formData,
           scope: 'system',
           target_id: null
         };
-        await api.post('/api/v2/credentials/', v2FormData);
+        await api.post('/api/system/credentials', createFormData);
         setSuccess('Credential set created successfully');
       }