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

tui/keybinds.go

@@ -0,0 +1,42 @@
+package tui
+
+type KeyAction int
+
+const (
+    KeyQuit KeyAction = iota
+    KeyStart
+    KeyStop
+    KeyToggleModule
+    KeyNextProfile
+    KeyPrevProfile
+    KeyFocusNext
+    KeyFocusPrev
+    KeyHistory
+    KeyStats
+    KeyHelp
+)
+
+type KeyBinding struct {
+    Key    string
+    Action KeyAction
+    Label  string
+}
+
+var DefaultKeyBindings = []KeyBinding{
+    {Key: "s", Action: KeyStart, Label: "start"},
+    {Key: "S", Action: KeyStop, Label: "stop"},
+    {Key: "tab", Action: KeyFocusNext, Label: "next"},
+    {Key: "shift+tab", Action: KeyFocusPrev, Label: "prev"},
+    {Key: "h", Action: KeyHistory, Label: "history"},
+    {Key: "?", Action: KeyHelp, Label: "help"},
+    {Key: "q", Action: KeyQuit, Label: "quit"},
+    {Key: "esc", Action: KeyQuit, Label: "quit"},
+}
+
+func HelpView() string {
+    s := "\n  Keys:\n"
+    for _, kb := range DefaultKeyBindings {
+        s += "    " + kb.Key + " — " + kb.Label + "\n"
+    }
+    return s
+}