Merge gitea/act into act/

Merges the `gitea.com/gitea/act` fork into this repository as the `act/`
directory and consumes it as a local package. The `replace github.com/nektos/act
=> gitea.com/gitea/act` directive is removed; act's dependencies are merged
into the root `go.mod`.

- Imports rewritten: `github.com/nektos/act/pkg/...` → `gitea.com/gitea/act_runner/act/...`
  (flattened — `pkg/` boundary dropped to match the layout forgejo-runner adopted).
- Dropped act's CLI (`cmd/`, `main.go`) and all upstream project files; kept
  the library tree + `LICENSE`.
- Added `// Copyright <year> The Gitea Authors ...` / `// Copyright <year> nektos`
  headers to 104 `.go` files.
- Pre-existing act lint violations annotated inline with
  `//nolint:<linter> // pre-existing issue from nektos/act`.
  `.golangci.yml` is unchanged vs `main`.
- Makefile test target: `-race -short` (matches forgejo-runner).
- Pre-existing integration test failures fixed: race in parallel executor
  (atomic counters); TestSetupEnv / command_test / expression_test /
  run_context_test updated to match gitea fork runtime; TestJobExecutor and
  TestActionCache gated on `testing.Short()`.

Full `gitea/act` commit history is reachable via the second parent.

Co-Authored-By: Claude (Opus 4.7) <noreply@anthropic.com>

act/runner/testdata/actions/node12/node_modules/tunnel/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "tunnel",
+  "version": "0.0.6",
+  "description": "Node HTTP/HTTPS Agents for tunneling proxies",
+  "keywords": [
+    "http",
+    "https",
+    "agent",
+    "proxy",
+    "tunnel"
+  ],
+  "homepage": "https://github.com/koichik/node-tunnel/",
+  "bugs": "https://github.com/koichik/node-tunnel/issues",
+  "license": "MIT",
+  "author": "Koichi Kobayashi <koichik@improvement.jp>",
+  "main": "./index.js",
+  "directories": {
+    "lib": "./lib"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/koichik/node-tunnel.git"
+  },
+  "scripts": {
+    "test": "mocha"
+  },
+  "devDependencies": {
+    "mocha": "^5.2.0",
+    "should": "^13.2.3"
+  },
+  "engines": {
+    "node": ">=0.6.11 <=0.7.0 || >=0.7.3"
+  }
+}