Initial commit: Stream Deck daemon with web UI

- Web-based key editor (Alpine.js SPA)
- Actions: shell commands, scripts, built-in media/volume/brightness, page switching
- Keyboard shortcut action (wtype/xdotool)
- On-device display with periodic command output
- Auto page switching (Hyprland, Sway, Niri, GNOME, KDE, X11)
- Screensaver with idle detection
- Config hot-reload
- Multi-device support

screensaver.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"log/slog"
+	"time"
+
+	"streamdeck-lets-go/internal/config"
+)
+
+type Screensaver struct {
+	enabled    bool
+	idleAfter  time.Duration
+	lastInput  time.Time
+	active     bool
+	savedBrightness int
+}
+
+func NewScreensaver(cfg *config.ScreensaverCfg) *Screensaver {
+	ss := &Screensaver{
+		enabled:   cfg.Enabled,
+		idleAfter: time.Duration(cfg.IdleSeconds) * time.Second,
+		lastInput: time.Now(),
+	}
+	if ss.idleAfter <= 0 {
+		ss.idleAfter = 30 * time.Second
+	}
+	return ss
+}
+
+func (ss *Screensaver) NotifyInput() {
+	ss.lastInput = time.Now()
+	if ss.active {
+		ss.active = false
+		slog.Debug("screensaver deactivated")
+	}
+}
+
+func (ss *Screensaver) Check() bool {
+	if !ss.enabled {
+		return false
+	}
+	if time.Since(ss.lastInput) > ss.idleAfter {
+		if !ss.active {
+			ss.active = true
+			slog.Debug("screensaver activated")
+			return true
+		}
+		return false
+	}
+	return false
+}
+
+func (ss *Screensaver) Activate(deck *Deck, cfg *config.ScreensaverCfg) {
+	ss.savedBrightness = deck.Brightness()
+
+	brightness := cfg.Brightness
+	if brightness <= 0 {
+		brightness = 10
+	}
+	if err := deck.SetBrightness(brightness); err != nil {
+		slog.Warn("screensaver: set brightness", "error", err)
+	}
+
+	if cfg.Image != "" {
+		img, err := loadImage(cfg.Image, 0, 0)
+		if err != nil {
+			slog.Warn("screensaver: load image", "path", cfg.Image, "error", err)
+			return
+		}
+		if err := deck.FillPanel(img); err != nil {
+			slog.Warn("screensaver: fill panel", "error", err)
+		}
+	}
+
+	slog.Info("screensaver activated")
+}
+
+func (ss *Screensaver) Deactivate(deck *Deck) {
+	brightness := ss.savedBrightness
+	if brightness <= 0 {
+		brightness = 75
+	}
+	if err := deck.SetBrightness(brightness); err != nil {
+		slog.Warn("screensaver: restore brightness", "error", err)
+	}
+	ss.savedBrightness = 0
+	slog.Info("screensaver deactivated")
+}
+
+func (ss *Screensaver) IsActive() bool {
+	return ss.active
+}