Add debug logging to container detection in sys/container.go

Add a package-level debug logger (logSys) to the sys package following
the project's pkg:filename naming convention. Add 4 meaningful debug log
calls to IsRunningInContainer() that trace which detection method (dockerenv
file, cgroup, or env var) triggered container detection, or confirm when no
container environment is found.

This helps developers and operators understand container detection behavior
at runtime with DEBUG=sys:* or DEBUG=* enabled.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

internal/sys/container.go

@@ -3,12 +3,19 @@ package sys
 import (
 	"os"
 	"strings"
+
+	"github.com/github/gh-aw-mcpg/internal/logger"
 )
 
+var logSys = logger.New("sys:container")
+
 // IsRunningInContainer detects if the current process is running inside a container.
 func IsRunningInContainer() bool {
+	logSys.Print("Detecting container environment")
+
 	// Method 1: Check for /.dockerenv file (Docker-specific)
 	if _, err := os.Stat("/.dockerenv"); err == nil {
+		logSys.Print("Container detected via /.dockerenv")
 		return true
 	}
 
@@ -20,14 +27,17 @@ func IsRunningInContainer() bool {
 			strings.Contains(content, "containerd") ||
 			strings.Contains(content, "kubepods") ||
 			strings.Contains(content, "lxc") {
+			logSys.Print("Container detected via /proc/1/cgroup")
 			return true
 		}
 	}
 
 	// Method 3: Check environment variable (set by Dockerfile)
 	if os.Getenv("RUNNING_IN_CONTAINER") == "true" {
+		logSys.Print("Container detected via RUNNING_IN_CONTAINER env var")
 		return true
 	}
 
+	logSys.Print("No container indicators found, running on host")
 	return false
 }