docs(openapi): add /admin/sys/{rate-limit,alerts,registration,retention}; mark /admin/config/* deprecated

Author: tevfik

cmd/server/openapi.yaml

@@ -2641,7 +2641,7 @@ paths:
               schema:
                 type: object
 
-  /admin/config/retention:
+  /admin/sys/retention:
     put:
       summary: Update data retention policy
       tags: [Admin]
@@ -2657,7 +2657,7 @@ paths:
         '200':
           description: Retention updated
 
-  /admin/config/rate-limit:
+  /admin/sys/rate-limit:
     put:
       summary: Update rate limit settings
       tags: [Admin]
@@ -2673,7 +2673,7 @@ paths:
         '200':
           description: Rate limit updated
 
-  /admin/config/alerts:
+  /admin/sys/alerts:
     put:
       summary: Update alert settings
       tags: [Admin]
@@ -2689,7 +2689,7 @@ paths:
         '200':
           description: Alerts updated
 
-  /admin/config/registration:
+  /admin/sys/registration:
     put:
       summary: Update registration settings
       tags: [Admin]
@@ -2705,6 +2705,76 @@ paths:
         '200':
           description: Registration updated
 
+  # Deprecated aliases — emit RFC 8594 Deprecation/Sunset/Link headers
+  # pointing at /admin/sys/* successors. Sunset: 2026-12-31.
+  /admin/config/retention:
+    put:
+      deprecated: true
+      summary: '[DEPRECATED] Use PUT /admin/sys/retention'
+      tags: [Admin]
+      security:
+        - BearerAuth: []
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/UpdateRetentionRequest'
+      responses:
+        '200':
+          description: Retention updated (deprecated path)
+
+  /admin/config/rate-limit:
+    put:
+      deprecated: true
+      summary: '[DEPRECATED] Use PUT /admin/sys/rate-limit'
+      tags: [Admin]
+      security:
+        - BearerAuth: []
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/UpdateRateLimitRequest'
+      responses:
+        '200':
+          description: Rate limit updated (deprecated path)
+
+  /admin/config/alerts:
+    put:
+      deprecated: true
+      summary: '[DEPRECATED] Use PUT /admin/sys/alerts'
+      tags: [Admin]
+      security:
+        - BearerAuth: []
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/UpdateAlertConfigRequest'
+      responses:
+        '200':
+          description: Alerts updated (deprecated path)
+
+  /admin/config/registration:
+    put:
+      deprecated: true
+      summary: '[DEPRECATED] Use PUT /admin/sys/registration'
+      tags: [Admin]
+      security:
+        - BearerAuth: []
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/UpdateRegistrationRequest'
+      responses:
+        '200':
+          description: Registration updated (deprecated path)
+
   /admin/mqtt/stats:
     get:
       summary: Get MQTT broker statistics