refactor web search config ownership into extensions

extensions/perplexity/openclaw.plugin.json

@@ -1,8 +1,40 @@
 {
   "id": "perplexity",
+  "uiHints": {
+    "webSearch.apiKey": {
+      "label": "Perplexity API Key",
+      "help": "Perplexity or OpenRouter API key for web search.",
+      "sensitive": true,
+      "placeholder": "pplx-..."
+    },
+    "webSearch.baseUrl": {
+      "label": "Perplexity Base URL",
+      "help": "Optional Perplexity/OpenRouter chat-completions base URL override."
+    },
+    "webSearch.model": {
+      "label": "Perplexity Model",
+      "help": "Optional Sonar/OpenRouter model override."
+    }
+  },
   "configSchema": {
     "type": "object",
     "additionalProperties": false,
-    "properties": {}
+    "properties": {
+      "webSearch": {
+        "type": "object",
+        "additionalProperties": false,
+        "properties": {
+          "apiKey": {
+            "type": ["string", "object"]
+          },
+          "baseUrl": {
+            "type": "string"
+          },
+          "model": {
+            "type": "string"
+          }
+        }
+      }
+    }
   }
 }