refactor(schema): flatten schemas directory structure

- Rename src/schemas/rpc.ts to src/schema.ts
- Update import paths in rpc-client.ts to use new location
- Remove schemas/ subdirectory

This simplifies the module structure by moving schema definitions
directly into the src root directory.

Author: ryoppippi

src/rpc-client.ts

@@ -5,11 +5,11 @@ import {
 	rpcActionRequestSchema,
 	rpcActionResponseSchema,
 	rpcClientConfigSchema,
-} from './schemas/rpc';
+} from './schema';
 import { StackOneAPIError } from './utils/errors';
 
 // Re-export types for consumers and to make types portable
-export type { RpcActionResponse } from './schemas/rpc';
+export type { RpcActionResponse } from './schema';
 
 /**
  * Custom RPC client for StackOne API.