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/index.js

@@ -1,11 +1,14 @@
-import {getInput, setOutput, setFailed} from '@actions/core';
-import {context} from '@actions/github';
+import {appendFileSync, readFileSync} from 'node:fs';
 
-try {
-  const nameToGreet = getInput('who-to-greet');
-  console.log(`Hello ${nameToGreet}!`);
-  setOutput('time', (new Date()).toTimeString());
-  console.log(`The event payload: ${JSON.stringify(context.payload, undefined, 2)}`);
-} catch (error) {
-  setFailed(error.message);
+const nameToGreet = process.env['INPUT_WHO-TO-GREET'] || 'World';
+console.log(`Hello ${nameToGreet}!`);
+
+if (process.env.GITHUB_OUTPUT) {
+  appendFileSync(process.env.GITHUB_OUTPUT, `time=${new Date().toTimeString()}\n`);
 }
+
+let payload = {};
+if (process.env.GITHUB_EVENT_PATH) {
+  payload = JSON.parse(readFileSync(process.env.GITHUB_EVENT_PATH, 'utf8'));
+}
+console.log(`The event payload: ${JSON.stringify(payload, undefined, 2)}`);