Onboarding detect provider from api key (#5955)

Co-authored-by: spencrmartin <spencermartin@squareup.com>
Co-authored-by: Michael Neale <michael.neale@gmail.com>

ui/desktop/openapi.json

@@ -585,6 +585,39 @@
         }
       }
     },
+    "/config/detect-provider": {
+      "post": {
+        "tags": [
+          "super::routes::config_management"
+        ],
+        "operationId": "detect_provider",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/DetectProviderRequest"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "Provider detected successfully",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/DetectProviderResponse"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "No matching provider found"
+          }
+        }
+      }
+    },
     "/config/extensions": {
       "get": {
         "tags": [
@@ -2774,6 +2807,35 @@
           }
         }
       },
+      "DetectProviderRequest": {
+        "type": "object",
+        "required": [
+          "api_key"
+        ],
+        "properties": {
+          "api_key": {
+            "type": "string"
+          }
+        }
+      },
+      "DetectProviderResponse": {
+        "type": "object",
+        "required": [
+          "provider_name",
+          "models"
+        ],
+        "properties": {
+          "models": {
+            "type": "array",
+            "items": {
+              "type": "string"
+            }
+          },
+          "provider_name": {
+            "type": "string"
+          }
+        }
+      },
       "EditMessageRequest": {
         "type": "object",
         "required": [