docs(api): add alert thresholds endpoints to swagger documentation

Add OpenAPI documentation for the new alert threshold management
endpoints used in traffic spike detection:

- GET /admin/alerts/thresholds - retrieve current threshold config
- PUT /admin/alerts/thresholds - update threshold configuration

Include AlertThresholdView and UpdateAlertThresholdsRequest schema
definitions with properties for QPS, RPM, TPM, RPD, TPD limits.

docs/swagger.yaml

@@ -443,6 +443,25 @@ definitions:
       warning:
         type: integer
     type: object
+  internal_api.AlertThresholdView:
+    properties:
+      global_qps:
+        type: integer
+      master_rpd:
+        type: integer
+      master_rpm:
+        type: integer
+      master_tpd:
+        type: integer
+      master_tpm:
+        type: integer
+      min_rpm_requests_1m:
+        type: integer
+      min_tpm_tokens_1m:
+        type: integer
+      updated_at:
+        type: integer
+    type: object
   internal_api.AlertView:
     properties:
       acked_at:
@@ -1045,6 +1064,23 @@ definitions:
       propagate_to_keys:
         type: boolean
     type: object
+  internal_api.UpdateAlertThresholdsRequest:
+    properties:
+      global_qps:
+        type: integer
+      master_rpd:
+        type: integer
+      master_rpm:
+        type: integer
+      master_tpd:
+        type: integer
+      master_tpm:
+        type: integer
+      min_rpm_requests_1m:
+        type: integer
+      min_tpm_tokens_1m:
+        type: integer
+    type: object
   internal_api.UpdateMasterRequest:
     properties:
       global_qps:
@@ -1517,6 +1553,56 @@ paths:
       summary: Alert statistics
       tags:
       - admin
+  /admin/alerts/thresholds:
+    get:
+      description: Get current alert threshold configuration for traffic spike detection
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            $ref: '#/definitions/internal_api.AlertThresholdView'
+        "500":
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/gin.H'
+      security:
+      - AdminAuth: []
+      summary: Get alert thresholds
+      tags:
+      - admin
+    put:
+      consumes:
+      - application/json
+      description: Update alert threshold configuration for traffic spike detection
+      parameters:
+      - description: Threshold configuration
+        in: body
+        name: request
+        required: true
+        schema:
+          $ref: '#/definitions/internal_api.UpdateAlertThresholdsRequest'
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            $ref: '#/definitions/internal_api.AlertThresholdView'
+        "400":
+          description: Bad Request
+          schema:
+            $ref: '#/definitions/gin.H'
+        "500":
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/gin.H'
+      security:
+      - AdminAuth: []
+      summary: Update alert thresholds
+      tags:
+      - admin
   /admin/api-keys:
     get:
       description: List API keys with optional filters