feat: enhance user API key management and implement soft delete

- Redirect users to API Keys tab after login instead of overview
- Remove Token Limit and Daily Cost Limit from user API key details modal
- Implement soft delete for API keys to preserve usage statistics
- Add admin endpoint to view deleted API keys with metadata
- Track deletion metadata (deletedBy, deletedAt, deletedByType)
- Ensure deleted API keys cannot be restored
- Include deleted key stats in user totals while excluding from active count

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

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

web/admin-spa/src/components/user/ViewApiKeyModal.vue

@@ -129,22 +129,6 @@
             </div>
           </div>
 
-          <!-- Limits -->
-          <div class="grid grid-cols-2 gap-4">
-            <div>
-              <label class="block text-sm font-medium text-gray-700">Token Limit</label>
-              <p class="mt-1 text-sm text-gray-900">
-                {{ apiKey.tokenLimit ? apiKey.tokenLimit.toLocaleString() : 'Unlimited' }}
-              </p>
-            </div>
-            <div>
-              <label class="block text-sm font-medium text-gray-700">Daily Cost Limit</label>
-              <p class="mt-1 text-sm text-gray-900">
-                {{ apiKey.dailyCostLimit ? `$${apiKey.dailyCostLimit.toFixed(2)}` : 'Unlimited' }}
-              </p>
-            </div>
-          </div>
-
           <!-- Usage Stats -->
           <div v-if="apiKey.usage" class="border-t border-gray-200 pt-4">
             <label class="mb-2 block text-sm font-medium text-gray-700">Usage Statistics</label>