break: update terminology from "Work" to "Focus"

- change mode from "Work" to "Focus" in server messages
- modify pomodoro configuration to use "Focus" instead of "Work"
- adjust default settings to reflect new terminology
- ensure all references to work duration are updated to focus duration
- update variable names in HTML and JavaScript for clarity

🤖

internal/websocket/client_commands.go

@@ -10,7 +10,7 @@ import (
 )
 
 func checkSettings(settings models.PomodoroConfig) bool {
-	return settings.Work > 0 && settings.ShortBreak > 0 && settings.LongBreak > 0 && settings.Sessions > 0
+	return settings.Focus > 0 && settings.ShortBreak > 0 && settings.LongBreak > 0 && settings.Sessions > 0
 }
 
 // Listens for commands from a client and handles them