refactor: restructure codebase to internal/ directory with modular architecture

- Move all source files to internal/{app,backend,config,executor,logger,parser,utils}
- Integrate third-party libraries: zerolog, goccy/go-json, gopsutil, cobra/viper
- Add comprehensive unit tests for utils package (94.3% coverage)
- Add performance benchmarks for string operations
- Fix error display: cleanup warnings no longer pollute Recent Errors
- Add GitHub Actions CI workflow
- Add Makefile for build automation
- Add README documentation

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Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

codeagent-wrapper/internal/logger/logger_suffix_test.go

@@ -0,0 +1,115 @@
+package logger
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestLoggerWithSuffixNamingAndIsolation(t *testing.T) {
+	tempDir := setTempDirEnv(t, t.TempDir())
+
+	taskA := "task-1"
+	taskB := "task-2"
+
+	loggerA, err := NewLoggerWithSuffix(taskA)
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix(%q) error = %v", taskA, err)
+	}
+	defer loggerA.Close()
+
+	loggerB, err := NewLoggerWithSuffix(taskB)
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix(%q) error = %v", taskB, err)
+	}
+	defer loggerB.Close()
+
+	wantA := filepath.Join(tempDir, fmt.Sprintf("%s-%d-%s.log", PrimaryLogPrefix(), os.Getpid(), taskA))
+	if loggerA.Path() != wantA {
+		t.Fatalf("loggerA path = %q, want %q", loggerA.Path(), wantA)
+	}
+
+	wantB := filepath.Join(tempDir, fmt.Sprintf("%s-%d-%s.log", PrimaryLogPrefix(), os.Getpid(), taskB))
+	if loggerB.Path() != wantB {
+		t.Fatalf("loggerB path = %q, want %q", loggerB.Path(), wantB)
+	}
+
+	if loggerA.Path() == loggerB.Path() {
+		t.Fatalf("expected different log files, got %q", loggerA.Path())
+	}
+
+	loggerA.Info("from taskA")
+	loggerB.Info("from taskB")
+	loggerA.Flush()
+	loggerB.Flush()
+
+	dataA, err := os.ReadFile(loggerA.Path())
+	if err != nil {
+		t.Fatalf("failed to read loggerA file: %v", err)
+	}
+	dataB, err := os.ReadFile(loggerB.Path())
+	if err != nil {
+		t.Fatalf("failed to read loggerB file: %v", err)
+	}
+
+	if !strings.Contains(string(dataA), "from taskA") {
+		t.Fatalf("loggerA missing its message, got: %q", string(dataA))
+	}
+	if strings.Contains(string(dataA), "from taskB") {
+		t.Fatalf("loggerA contains loggerB message, got: %q", string(dataA))
+	}
+	if !strings.Contains(string(dataB), "from taskB") {
+		t.Fatalf("loggerB missing its message, got: %q", string(dataB))
+	}
+	if strings.Contains(string(dataB), "from taskA") {
+		t.Fatalf("loggerB contains loggerA message, got: %q", string(dataB))
+	}
+}
+
+func TestLoggerWithSuffixReturnsErrorWhenTempDirNotWritable(t *testing.T) {
+	base := t.TempDir()
+	noWrite := filepath.Join(base, "ro")
+	if err := os.Mkdir(noWrite, 0o500); err != nil {
+		t.Fatalf("failed to create read-only temp dir: %v", err)
+	}
+	t.Cleanup(func() { _ = os.Chmod(noWrite, 0o700) })
+	setTempDirEnv(t, noWrite)
+
+	logger, err := NewLoggerWithSuffix("task-err")
+	if err == nil {
+		_ = logger.Close()
+		t.Fatalf("expected error when temp dir is not writable")
+	}
+}
+
+func TestLoggerWithSuffixSanitizesUnsafeSuffix(t *testing.T) {
+	tempDir := setTempDirEnv(t, t.TempDir())
+
+	raw := "../bad id/with?chars"
+	safe := sanitizeLogSuffix(raw)
+	if safe == "" {
+		t.Fatalf("sanitizeLogSuffix returned empty string")
+	}
+	if strings.ContainsAny(safe, "/\\") {
+		t.Fatalf("sanitized suffix should not contain path separators, got %q", safe)
+	}
+
+	logger, err := NewLoggerWithSuffix(raw)
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix(%q) error = %v", raw, err)
+	}
+	t.Cleanup(func() {
+		_ = logger.Close()
+		_ = os.Remove(logger.Path())
+	})
+
+	wantBase := fmt.Sprintf("%s-%d-%s.log", PrimaryLogPrefix(), os.Getpid(), safe)
+	if gotBase := filepath.Base(logger.Path()); gotBase != wantBase {
+		t.Fatalf("log filename = %q, want %q", gotBase, wantBase)
+	}
+	if dir := filepath.Dir(logger.Path()); dir != tempDir {
+		t.Fatalf("logger path dir = %q, want %q", dir, tempDir)
+	}
+}