chore(scripts): drop the plumbing the consolidation left dead

Round 4. Two leftovers from moving the build into the shared helper, both
invisible here because `scripts/` is prettier-gated but not ESLint-gated,
so an unused binding fails nothing:

- smoke-web-elicitation.mjs imported `existsSync` solely for the local
  early return that is gone.
- pack-and-verify.mjs kept `composableServer` and its `composableServerPath`
  import for the same reason; the helper now asserts that entry via
  `requires: ["composable"]`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JTHVxSu8AUgHRLvo1ntZ8H
Signed-off-by: cliffhall <cliff@futurescale.com>

scripts/smoke-web-elicitation.mjs

@@ -32,7 +32,7 @@
  */
 
 import { spawn } from "node:child_process";
-import { existsSync, mkdirSync } from "node:fs";
+import { mkdirSync } from "node:fs";
 import { createRequire } from "node:module";
 import { setTimeout as delay } from "node:timers/promises";
 import { join, resolve } from "node:path";