cli: add orca plugin create, validate and inspect (#36280)

* cli: add orca plugin create, validate and inspect

* build: ship orca plugin validate's main checks as a CLI main entry

src/cli/cli-exit-code.ts

@@ -0,0 +1,13 @@
+import { cliErrorCode } from './cli-error'
+
+const PLUGIN_EXIT_CODES: Readonly<Record<string, number>> = {
+  plugin_invalid: 2,
+  approval_required: 3,
+  approval_stale: 3
+}
+
+/** `orca plugin` exit codes are a stable contract so scripts can tell "invalid" and "ask a human" apart from failure. */
+export function cliErrorExitCode(error: unknown, commandPath: readonly string[]): number {
+  const code = cliErrorCode(error)
+  return commandPath[0] === 'plugin' && code ? (PLUGIN_EXIT_CODES[code] ?? 1) : 1
+}