feat: make admin user edit page fields editable (username, email, name)

The admin-user-edit page had display-only fields for username, email,
first name, and last name. Convert to editable form inputs with:
- Dirty detection (unsaved changes indicator)
- Only sends changed fields in PUT payload
- Validation error display per field
- Save button disabled when no changes

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

app/modules/tenancy/static/admin/js/admin-user-edit.js

@@ -18,6 +18,14 @@ function adminUserEditPage() {
         userId: null,
         currentUserId: null,
 
+        // Editable profile form
+        editForm: {
+            username: '',
+            email: '',
+            first_name: '',
+            last_name: ''
+        },
+
         // Platform assignment state
         showPlatformModal: false,
         availablePlatforms: [],
@@ -98,6 +106,14 @@ function adminUserEditPage() {
                     full_name: [response.first_name, response.last_name].filter(Boolean).join(' ') || null
                 };
 
+                // Populate editable form
+                this.editForm = {
+                    username: this.adminUser.username || '',
+                    email: this.adminUser.email || '',
+                    first_name: this.adminUser.first_name || '',
+                    last_name: this.adminUser.last_name || ''
+                };
+
                 adminUserEditLog.info(`Admin user loaded in ${duration}ms`, {
                     id: this.adminUser.id,
                     username: this.adminUser.username,
@@ -141,6 +157,78 @@ function adminUserEditPage() {
             return Utils.formatDate(dateString);
         },
 
+        // Check if profile form has unsaved changes
+        get profileDirty() {
+            if (!this.adminUser) return false;
+            return this.editForm.username !== (this.adminUser.username || '') ||
+                   this.editForm.email !== (this.adminUser.email || '') ||
+                   this.editForm.first_name !== (this.adminUser.first_name || '') ||
+                   this.editForm.last_name !== (this.adminUser.last_name || '');
+        },
+
+        // Save profile changes
+        async saveProfile() {
+            adminUserEditLog.info('Saving profile changes...');
+            this.errors = {};
+
+            // Build update payload with only changed fields
+            const payload = {};
+            if (this.editForm.username !== (this.adminUser.username || '')) {
+                payload.username = this.editForm.username;
+            }
+            if (this.editForm.email !== (this.adminUser.email || '')) {
+                payload.email = this.editForm.email;
+            }
+            if (this.editForm.first_name !== (this.adminUser.first_name || '')) {
+                payload.first_name = this.editForm.first_name;
+            }
+            if (this.editForm.last_name !== (this.adminUser.last_name || '')) {
+                payload.last_name = this.editForm.last_name;
+            }
+
+            if (Object.keys(payload).length === 0) return;
+
+            this.saving = true;
+            try {
+                const url = `/admin/users/${this.userId}`;
+                window.LogConfig.logApiCall('PUT', url, payload, 'request');
+
+                const response = await apiClient.put(url, payload);
+
+                window.LogConfig.logApiCall('PUT', url, response, 'response');
+
+                // Update local state
+                this.adminUser.username = response.username;
+                this.adminUser.email = response.email;
+                this.adminUser.first_name = response.first_name;
+                this.adminUser.last_name = response.last_name;
+                this.adminUser.full_name = [response.first_name, response.last_name].filter(Boolean).join(' ') || null;
+
+                // Re-sync form
+                this.editForm = {
+                    username: response.username || '',
+                    email: response.email || '',
+                    first_name: response.first_name || '',
+                    last_name: response.last_name || ''
+                };
+
+                Utils.showToast('Profile updated successfully', 'success');
+                adminUserEditLog.info('Profile updated successfully');
+
+            } catch (error) {
+                window.LogConfig.logError(error, 'Save Profile');
+                if (error.details) {
+                    for (const detail of error.details) {
+                        const field = detail.loc?.[detail.loc.length - 1];
+                        if (field) this.errors[field] = detail.msg;
+                    }
+                }
+                Utils.showToast(error.message || 'Failed to save profile', 'error');
+            } finally {
+                this.saving = false;
+            }
+        },
+
         // Toggle super admin status
         async toggleSuperAdmin() {
             const isSuperAdmin = this.adminUser.role === 'super_admin';