test: make TestRunEvent integration suite runnable locally (#987)

The `TestRunEvent*` integration tests are skipped in CI (`make test` runs `-short`), which hid several breakages that make them fail when run locally:

- `runTest` built the runner `Config` without `ContainerMaxLifetime`, so the job container ran `/bin/sleep 0` and exited immediately — every step failed with "container is not running". Set it to 1h.
- The root `.gitignore`'s unscoped `.env` and `dist` rules shadowed fixtures under `testdata/`. Anchored `dist` → `/dist` (the goreleaser output) and un-ignored `testdata/secrets/.env`.
- Added the missing `testdata/secrets/.env` fixture for `TestRunEventSecrets`.
- The `node24` local action referenced a `dist/index.js` bundle that was never committed (and was gitignored). Made the fixture self-contained (dependency-free ESM, `main: index.js`) so it runs without an `ncc` build. If you'd rather keep the `@actions/core`-based action and commit the built bundle instead, happy to switch.

Network-dependent subtests (remote `uses:`/composite actions) are out of scope.

---
This PR was written with the help of Claude Opus 4.7

---------

Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/987
Reviewed-by: Nicolas <bircni@icloud.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

act/runner/testdata/actions/node24/package.json

@@ -1,21 +1,5 @@
 {
   "name": "node24",
-  "version": "1.0.0",
-  "description": "",
-  "main": "index.js",
-  "type": "module",
-  "scripts": {
-    "build": "ncc build index.js"
-  },
-  "license": "ISC",
-  "dependencies": {
-    "@actions/core": "^3.0.1",
-    "@actions/github": "^9.1.1"
-  },
-  "devDependencies": {
-    "@vercel/ncc": "^0.38.4"
-  },
-  "engines": {
-    "node": ">=24"
-  }
+  "private": true,
+  "type": "module"
 }