fix(mcp): preserve custom fields in Codex TOML config editor

Fixed an issue where custom/extension fields (e.g., timeout_ms, retry_count)
were silently dropped when editing Codex MCP server configurations in TOML format.

Root cause: The TOML parser functions only extracted known fields (type, command,
args, env, cwd, url, headers), discarding any additional fields during normalization.

Changes:
- mcpServerToToml: Now uses spread operator to copy all fields before stringification
- normalizeServerConfig: Added logic to preserve unknown fields after processing known ones
- Both stdio and http server types now retain custom configuration fields

This fix enables forward compatibility with future MCP protocol extensions and
allows users to add custom configurations without code changes.

src/components/providers/forms/ProviderForm.tsx

@@ -3,12 +3,7 @@ import { useForm } from "react-hook-form";
 import { zodResolver } from "@hookform/resolvers/zod";
 import { useTranslation } from "react-i18next";
 import { Button } from "@/components/ui/button";
-import {
-  Form,
-  FormField,
-  FormItem,
-  FormMessage,
-} from "@/components/ui/form";
+import { Form, FormField, FormItem, FormMessage } from "@/components/ui/form";
 import { providerSchema, type ProviderFormData } from "@/lib/schemas/provider";
 import type { AppId } from "@/lib/api";
 import type { ProviderCategory, ProviderMeta } from "@/types";