feat(server): add revealHttpAuthLiterals API and enhance web interface for credential management

- Implemented revealHttpAuthLiterals function to return plaintext credential fields from HTTP auth configurations.
- Added a new endpoint in the HTTP auths API to reveal credentials securely.
- Updated the web interface to fetch and display plaintext literals, improving user experience for managing credentials.
- Enhanced CredentialFields component to support revealing and masking credential values dynamically.

packages/web/src/api/hooks.js

@@ -383,3 +383,8 @@ export function useDeleteHttpAuth() {
     onSuccess: () => qc.invalidateQueries({ queryKey: ["http-auths"] }),
   });
 }
+
+/** Fetch plaintext literals only (not encrypted secrets). */
+export async function fetchHttpAuthLiterals(name) {
+  return (await api.get(`/http-auths/${encodeURIComponent(name)}/reveal`)).data;
+}