refactor: break up large functions, add RPG/league/salary/burnout, fix bugs, add tests

- Refactor GenerateMonthlyReport (198→70), HandleCallback (128→85),
  handleHistoryCallback (131→38), handleExportCallback (100→25),
  checkAchievements (86→25) into extracted helper functions
- Add RPG system (XP, levels, streak, achievements, burnout)
- Add WorkTime League leaderboard
- Add salary estimation with configurable currency/rate
- Add input sanitization (SanitizeNote, SanitizeDisplayName)
- Add settings select-style pickers for toggles (report, RPG, league)
- Add break threshold inline picker UI
- Add event notes with pending state and /note command
- Add multi-calendar support (Jalali, Hijri)
- Add Excel export with theme picker
- Fix: getTodayBreakThreshold uses user's timezone (was UTC)
- Fix: acknowledgeCallback passes real callback ID
- Fix: currency symbol safety with currencySymbol() helper
- Fix: count work hours in summary on day-off days
- Fix: unsilence all error returns from SQL Exec/Bot API/migrations
- Remove stale db/schema.sql and unreferenced computeWeekTotals
- Extract constants: DateLayout, TimeLayout, secondsPerHour, etc.
- Add 12 new tests (XP, salary, sanitize, currency, dateutil)
- Remove duplicate package doc comment in totals.go

internal/bot/totals.go

@@ -1,5 +1,3 @@
-// Package bot implements the Telegram bot logic: message routing, time tracking,
-// calendar rendering, Excel export, and inline editing of events.
 package bot
 
 import (