feat(git-master): validate git_env_prefix values

src/config/schema/git-master.ts

@@ -1,12 +1,14 @@
 import { z } from "zod"
 
+import { GitEnvPrefixSchema } from "./git-env-prefix"
+
 export const GitMasterConfigSchema = z.object({
   /** Add "Ultraworked with Sisyphus" footer to commit messages (default: true). Can be boolean or custom string. */
   commit_footer: z.union([z.boolean(), z.string()]).default(true),
   /** Add "Co-authored-by: Sisyphus" trailer to commit messages (default: true) */
   include_co_authored_by: z.boolean().default(true),
   /** Environment variable prefix for all git commands (default: "GIT_MASTER=1"). Set to "" to disable. Allows custom git hooks to detect git-master skill usage. */
-  git_env_prefix: z.string().default("GIT_MASTER=1"),
+  git_env_prefix: GitEnvPrefixSchema,
 })
 
 export type GitMasterConfig = z.infer<typeof GitMasterConfigSchema>