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/uses-composite-with-pre-and-post-steps/action-with-pre-and-post/action.yml

@@ -0,0 +1,13 @@
+name: "Action with pre and post"
+description: "Action with pre and post"
+
+inputs:
+  step:
+    description: "step"
+    required: true
+
+runs:
+  using: "node16"
+  pre: pre.js
+  main: main.js
+  post: post.js

act/runner/testdata/uses-composite-with-pre-and-post-steps/action-with-pre-and-post/main.js

@@ -0,0 +1,3 @@
+const { appendFileSync } = require('fs');
+const step = process.env['INPUT_STEP'];
+appendFileSync(process.env['GITHUB_ENV'], `;${step}`, { encoding:'utf-8' })

act/runner/testdata/uses-composite-with-pre-and-post-steps/action-with-pre-and-post/post.js

@@ -0,0 +1,3 @@
+const { appendFileSync } = require('fs');
+const step = process.env['INPUT_STEP'];
+appendFileSync(process.env['GITHUB_ENV'], `;${step}-post`, { encoding:'utf-8' })

act/runner/testdata/uses-composite-with-pre-and-post-steps/action-with-pre-and-post/pre.js

@@ -0,0 +1 @@
+console.log('pre');

act/runner/testdata/uses-composite-with-pre-and-post-steps/composite_action/action.yml

@@ -0,0 +1,12 @@
+name: "Test Composite Action"
+description: "Test action uses composite"
+
+runs:
+  using: "composite"
+  steps:
+  - uses: ./uses-composite-with-pre-and-post-steps/action-with-pre-and-post
+    with:
+      step: step1
+  - uses: ./uses-composite-with-pre-and-post-steps/action-with-pre-and-post
+    with:
+      step: step2

act/runner/testdata/uses-composite-with-pre-and-post-steps/last-action/action.yml

@@ -0,0 +1,7 @@
+name: "last action check"
+description: "last action check"
+
+runs:
+  using: "node16"
+  main: main.js
+  post: post.js

act/runner/testdata/uses-composite-with-pre-and-post-steps/last-action/post.js

@@ -0,0 +1,7 @@
+const output = process.env['STEP_OUTPUT_TEST'];
+const expected = 'empty;step1;step2;step2-post;step1-post';
+
+console.log(output);
+if (output !== expected) {
+  throw new Error(`Expected '${expected}' but got '${output}'`);
+}

act/runner/testdata/uses-composite-with-pre-and-post-steps/push.yml

@@ -0,0 +1,11 @@
+name: uses-composite-with-pre-and-post-steps
+on: push
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: ./uses-composite-with-pre-and-post-steps/last-action
+      - uses: actions/checkout@v2
+      - run: echo -n "STEP_OUTPUT_TEST=empty" >> $GITHUB_ENV
+      - uses: ./uses-composite-with-pre-and-post-steps/composite_action