Merge pull request '#54 follow-up: pretest:e2e cleans out/test (stop stale cross-branch compiled tests running)' (#56) from s54-pretest-clean into main

`tsc -p tsconfig.e2e.json` emits to `out/` but never removes outputs for test
sources absent on the current branch, so stale compiled
`out/test/e2e/suite/*.test.js` from other branches were picked up and run by the
suite glob (`**/*.test.js`) — this caused real cross-branch test confusion in
session 0048 (a deleted probe + another branch's tests ran on an unrelated branch).

Add a `clean:e2e` script (`fs.rmSync('out/test', {recursive, force})` via node, so
no shell `rm` dependency) and run it between `build` and `tsc` in `pretest:e2e`.
Cleans ONLY `out/test` — never `out/`, which holds the just-built esbuild bundle
(`out/extension.cjs`, `out/media`).

Verified: planting a stale `out/test/.../zz.test.js` then running `pretest:e2e`
removes it, and the E2E suite stays green (73 passing + 1 pending, both passes
exit 0).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package.json

@@ -202,7 +202,8 @@
     "watch": "node esbuild.mjs --watch",
     "typecheck": "tsc --noEmit",
     "test": "vitest run",
-    "pretest:e2e": "npm run build && tsc -p tsconfig.e2e.json",
+    "clean:e2e": "node -e \"require('fs').rmSync('out/test',{recursive:true,force:true})\"",
+    "pretest:e2e": "npm run build && npm run clean:e2e && tsc -p tsconfig.e2e.json",
     "test:e2e": "node ./out/test/e2e/runTest.js",
     "smoke:live": "npm run build && node scripts/smoke-live-turn.mjs",
     "vscode:prepublish": "node esbuild.mjs"