feat: initial gosleep-timer implementation

Go TUI sleep timer with modular architecture.
- Config: YAML-based, profile inheritance, auto WM detection
- Engine: timer, executor, stage pipeline (pre→timer→post)
- Modules: workspace (niri/hyprland/kde), media, lock, kill,
  notify, sound, brightness, mute, custom, script
- TUI: bubbletea app with profiles, module toggles, progress bar
- CLI: run, list-profiles, export, import, history, stats
- History: JSONL log with statistics
- QR: config export as ASCII QR

history/history.go

@@ -0,0 +1,85 @@
+package history
+
+import (
+	"bufio"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+type Record struct {
+	Timestamp time.Time `json:"ts"`
+	Profile   string    `json:"profile"`
+	Duration  string    `json:"duration"`
+	Status    string    `json:"status"` // completed, killed, error
+	Error     string    `json:"error,omitempty"`
+}
+
+type Log struct {
+	path string
+	file *os.File
+}
+
+func DefaultPath() (string, error) {
+	// $XDG_DATA_HOME/gosleep-timer/history.jsonl
+	// fallback ~/.local/share/gosleep-timer/history.jsonl
+	dataHome := os.Getenv("XDG_DATA_HOME")
+	if dataHome == "" {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return "", err
+		}
+		dataHome = filepath.Join(home, ".local", "share")
+	}
+	dir := filepath.Join(dataHome, "gosleep-timer")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "history.jsonl"), nil
+}
+
+func Open(path string) (*Log, error) {
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return nil, err
+	}
+	return &Log{path: path, file: f}, nil
+}
+
+func (l *Log) Append(r Record) error {
+	r.Timestamp = time.Now().UTC()
+	data, err := json.Marshal(r)
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintln(l.file, string(data))
+	return err
+}
+
+func (l *Log) Close() error {
+	return l.file.Close()
+}
+
+func ReadAll(path string) ([]Record, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []Record{}, nil
+		}
+		return nil, err
+	}
+	defer f.Close()
+
+	var records []Record
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		var r Record
+		if err := json.Unmarshal(scanner.Bytes(), &r); err != nil {
+			continue // skip corrupt lines
+		}
+		records = append(records, r)
+	}
+	return records, scanner.Err()
+}