docs(cli): mirror branches get note in legacy TS shell

The legacy TypeScript shell is a 1:1 port of the Go CLI and must keep
help text in sync. Match the new main-branch password-field note that
was added to the Go cobra command.

Fixes CLI-1450

Author: claude

apps/cli/src/legacy/commands/branches/get/get.command.ts

@@ -16,7 +16,9 @@ const config = {
 export type LegacyBranchesGetFlags = CliCommand.Command.Config.Infer<typeof config>;
 
 export const legacyBranchesGetCommand = Command.make("get", config).pipe(
-  Command.withDescription("Retrieve details of the specified preview branch."),
+  Command.withDescription(
+    "Retrieve details of the specified preview branch.\n\nNote: For the main branch, password-dependent fields (POSTGRES_URL, POSTGRES_URL_NON_POOLING) are not populated because production database credentials are not retrievable via API.",
+  ),
   Command.withShortDescription("Retrieve details of a preview branch"),
   Command.withHandler((flags) => legacyBranchesGet(flags)),
 );