refactor: move act/model and act/exprparser to actionslib (#1143)

Gitea needs the workflow model and the expression evaluator to parse workflows and to build the task payload this runner consumes, so today it depends on `gitea.com/gitea/runner` just for `act/model` and `act/exprparser`. Both packages now live in `gitea.dev/actionslib` (`pkg/model`, `pkg/exprparser`), the module both sides already share, and this repository consumes them from there.

### Changes

- `act/model` and `act/exprparser` are deleted, all imports point at `gitea.dev/actionslib/pkg/...`.
- New `act/ghcontext` package: the `GithubContext` helpers that need a git checkout on disk (`SetRef`, `SetSha`, `SetRepositoryAndOwner`) are runner only and would drag a git client plus the act context logger into the shared module, so they stay here as functions, with their tests. Only caller is `RunContext.getGithubContext`.
- `act/common.CartesianProduct` moved to the shared model package, `act/model` was its only user.
- `act/model/testdata/container-volumes` moved to `act/runner/testdata/container-volumes`, its only user is `runner_test.go`.
- `internal/pkg/client.UUIDHeader` / `TokenHeader` now alias `pkg/protocol`, so the header names cannot drift apart from Gitea.

### Notes

- No behaviour change intended: the moved files are unchanged apart from the import paths and the split described above.
- `go.mod` depends on the released `gitea.dev/actionslib v0.7.0`, which carries both https://gitea.com/gitea/actionslib/pulls/11 and the `model.UsesHash` port in https://gitea.com/gitea/actionslib/pulls/14 that `main` needs after https://gitea.com/gitea/runner/pulls/1150.
- Verified with `go build ./...`, `go vet ./...` and `go test ./act/... ./internal/...`; the docker based `act/runner` integration tests (`TestRunEvent`, `TestRunMatrixWithUserDefinedInclusions`) fail identically with and without this change in my environment.

Assisted-by: Codet:GPT-5.1-Codex
Reviewed-on: https://gitea.com/gitea/runner/pulls/1143
Reviewed-by: silverwind <[email protected]>

act/runner/expression_test.go

@@ -9,9 +9,8 @@ import (
 	"strings"
 	"testing"
 
-	"gitea.com/gitea/runner/act/exprparser"
-	"gitea.com/gitea/runner/act/model"
-
+	"gitea.dev/actionslib/pkg/exprparser"
+	"gitea.dev/actionslib/pkg/model"
 	assert "github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	yaml "go.yaml.in/yaml/v4"
@@ -279,41 +278,6 @@ func TestInterpolate(t *testing.T) {
 	}
 }
 
-func TestSplitSubExpressions(t *testing.T) {
-	expr := func(text string) exprPart { return exprPart{text: text, isExpr: true} }
-	literal := func(text string) exprPart { return exprPart{text: text} }
-
-	for _, tt := range []struct {
-		in   string
-		want []exprPart
-	}{
-		{"Hello World", []exprPart{literal("Hello World")}},
-		{"${{ true }}", []exprPart{expr("true")}},
-		{"${{ true }} ${{ false }}", []exprPart{expr("true"), literal(" "), expr("false")}},
-		{"Hello ${{ 'World' }}", []exprPart{literal("Hello "), expr("'World'")}},
-		// a quote toggles string state, so a `}}` inside a string does not end the expression
-		{"${{ '}}' }}", []exprPart{expr("'}}'")}},
-		{"${{ '''}}''' }}", []exprPart{expr("'''}}'''")}},
-		{"${{ '''' }}", []exprPart{expr("''''")}},
-		{`${{ fromJSON('"}}"') }}`, []exprPart{expr(`fromJSON('"}}"')`)}},
-		{`${{ fromJSON('"\"}}\""') }}`, []exprPart{expr(`fromJSON('"\"}}\""')`)}},
-		{`${{ fromJSON('"''}}"') }}`, []exprPart{expr(`fromJSON('"''}}"')`)}},
-		// without a complete literal the value stays text, as GitHub's template reader leaves it
-		{"${{ 1", []exprPart{literal("${{ 1")}},
-		// a malformed part stays one part, so it cannot restructure its neighbours
-		{"${{ 1) && (2 }}", []exprPart{expr("1) && (2")}},
-	} {
-		got, err := splitSubExpressions(tt.in)
-		require.NoError(t, err, tt.in)
-		assert.Equal(t, tt.want, got, tt.in)
-	}
-
-	for _, in := range []string{"${{ 'a' }} ${{ b", "${{ 'a }}"} {
-		_, err := splitSubExpressions(in)
-		assert.ErrorContains(t, err, "unclosed expression", in)
-	}
-}
-
 func TestGetEvaluatorInputsBoolean(t *testing.T) {
 	workflows := map[string]string{
 		"workflow_call": `