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/common/outbound_ip.go

@@ -0,0 +1,79 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// Copyright 2021 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package common
+
+import (
+	"net"
+	"sort"
+	"strings"
+)
+
+// GetOutboundIP returns an outbound IP address of this machine.
+// It tries to access the internet and returns the local IP address of the connection.
+// If the machine cannot access the internet, it returns a preferred IP address from network interfaces.
+// It returns nil if no IP address is found.
+func GetOutboundIP() net.IP {
+	// See https://stackoverflow.com/a/37382208
+	conn, err := net.Dial("udp", "8.8.8.8:80")
+	if err == nil {
+		defer conn.Close()
+		return conn.LocalAddr().(*net.UDPAddr).IP
+	}
+
+	// So the machine cannot access the internet. Pick an IP address from network interfaces.
+	if ifs, err := net.Interfaces(); err == nil {
+		type IP struct {
+			net.IP
+			net.Interface
+		}
+		var ips []IP
+		for _, i := range ifs {
+			if addrs, err := i.Addrs(); err == nil {
+				for _, addr := range addrs {
+					var ip net.IP
+					switch v := addr.(type) {
+					case *net.IPNet:
+						ip = v.IP
+					case *net.IPAddr:
+						ip = v.IP
+					}
+					if ip.IsGlobalUnicast() {
+						ips = append(ips, IP{ip, i})
+					}
+				}
+			}
+		}
+		if len(ips) > 1 {
+			sort.Slice(ips, func(i, j int) bool {
+				ifi := ips[i].Interface
+				ifj := ips[j].Interface
+
+				// ethernet is preferred
+				if vi, vj := strings.HasPrefix(ifi.Name, "e"), strings.HasPrefix(ifj.Name, "e"); vi != vj {
+					return vi
+				}
+
+				ipi := ips[i].IP
+				ipj := ips[j].IP
+
+				// IPv4 is preferred
+				if vi, vj := ipi.To4() != nil, ipj.To4() != nil; vi != vj {
+					return vi
+				}
+
+				// en0 is preferred to en1
+				if ifi.Name != ifj.Name {
+					return ifi.Name < ifj.Name
+				}
+
+				// fallback
+				return ipi.String() < ipj.String()
+			})
+			return ips[0].IP
+		}
+	}
+
+	return nil
+}