refactor(auth): replace z.enum with plain TS union; drop zod dependency

AuthProvider was the only zod usage in the package — a z.enum solely to
infer a type. Replace with a plain union type and remove zod from
packages/auth/package.json dependencies.

Claude-Session: https://claude.ai/code/session_012Bnvt1MghwHj4qQRxuQUGa

packages/auth/package.json

@@ -28,8 +28,7 @@
 		"better-auth": "1.6.23",
 		"drizzle-orm": "1.0.0-rc.4",
 		"jose": "^6.2.3",
-		"react": "^19.2.7",
-		"zod": "^4.4.3"
+		"react": "^19.2.7"
 	},
 	"devDependencies": {
 		"@reactive-resume/config": "workspace:*",

packages/auth/src/types.ts

@@ -1,11 +1,9 @@
 import type { auth } from "./config";
-import z from "zod";
 
 export type AuthSession = {
 	session: typeof auth.$Infer.Session.session;
 	user: typeof auth.$Infer.Session.user;
 };
 
-const authProviderSchema = z.enum(["credential", "passkey", "google", "github", "linkedin", "custom"]);
-
-export type AuthProvider = z.infer<typeof authProviderSchema>;
+// ponytail: plain union replaces z.enum solely used for type inference
+export type AuthProvider = "credential" | "passkey" | "google" | "github" | "linkedin" | "custom";

pnpm-lock.yaml

@@ -706,9 +706,6 @@ importers:
       react:
         specifier: ^19.2.7
         version: 19.2.7
-      zod:
-        specifier: ^4.4.3
-        version: 4.4.3
     devDependencies:
       '@reactive-resume/config':
         specifier: workspace:*