docs(api): mark collection responses nullable (#6430)

* docs(api): mark collection responses nullable

Describe allLinks and panel log response objects as nullable string arrays so generated clients accept the existing nil-slice wire format. Pin both schemas with buildSpec regression assertions and regenerate the OpenAPI copies.

* docs(api): include nullable Xray log responses

Allow generated response arrays to opt into nullability while retaining their schema references and Go-derived examples. Apply this to Xray logs, whose nil slices already serialize as null, and pin the schema and example through buildSpec.

frontend/public/openapi.json

@@ -4340,7 +4340,13 @@
                     "msg": {
                       "type": "string"
                     },
-                    "obj": {}
+                    "obj": {
+                      "type": "array",
+                      "nullable": true,
+                      "items": {
+                        "type": "string"
+                      }
+                    }
                   }
                 },
                 "example": {
@@ -6399,6 +6405,7 @@
                     },
                     "obj": {
                       "type": "array",
+                      "nullable": true,
                       "items": {
                         "type": "string"
                       }
@@ -6480,6 +6487,7 @@
                     },
                     "obj": {
                       "type": "array",
+                      "nullable": true,
                       "items": {
                         "$ref": "#/components/schemas/LogEntry"
                       }