feat(economy): add /lottery - daily draw, weighted winner takes the pot

Buy tickets (200 coins each, max 100/draw); one winner is drawn daily at 21:00
Tallinn time weighted by ticket count and credited the whole pot. Coin-conserving
by design: each ticket's cost is deducted at purchase and the winner is minted
exactly the sum of all ticket spend - no shared pot record, so no cross-period
race. Ticket state lives per-user keyed by draw period (full scan only at draw
time and for the pot view).

- New lottery.py: TICKET_COST/MAX_TICKETS/DRAW_HOUR, pure period_for, and
  do_buy_ticket / get_lottery_state / do_lottery_draw. New lottery_tickets +
  lottery_period schema fields (period added to _TEXT_FIELDS).
- /lottery [kogus] command (view or buy) with full failure handling.
- Scheduled lottery_draw_daily loop in bot.py (both profiles; each draws its own
  collection), announcing to the optional LOTTERY_CHANNEL_ID (config + .env).

14 tests: period boundary, buy/accumulate/reset/caps/guards, pot state, draw
payout with coin conservation, and the more-tickets-wins-more weighting.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013VbAVsrZuYesea99mPMmPT

strings/economy.py

@@ -21,6 +21,7 @@ __all__ = [
     'LOOTBOX_UI',
     'BANK_UI',
     'ACHIEVEMENTS_UI',
+    'LOTTERY_UI',
     'JAILED_UI',
     'SHOP_BTN',
     'DAILY_UI',
@@ -302,6 +303,26 @@ ACHIEVEMENTS_UI: dict[str, str] = {
     "unlocked_note": "🎉 **Uued saavutused avatud:** {names}\n💰 Preemia: +{reward}",
 }
 
+# ---------------------------------------------------------------------------
+# Lottery  (daily draw; one weighted winner takes the pot)
+# ---------------------------------------------------------------------------
+LOTTERY_UI: dict[str, str] = {
+    "title":        "🎟️ TipiLOTO",
+    "desc":         "Osta pileteid ja võida kogu pott! Loosimine iga päev **{draw_time}**. Iga pilet = **{cost}**, rohkem pileteid = suurem võiduvõimalus.",
+    "f_pot":        "💰 Praegune pott",
+    "f_players":    "👥 Osalejaid",
+    "f_your":       "🎟️ Sinu piletid",
+    "your_val":     "{tickets} tk  ·  võiduvõimalus **{chance}%**",
+    "your_none":    "Sul pole veel pileteid. Osta käsuga `/lottery <kogus>`.",
+    "bought":       "🎟️ Ostsid **{count}** piletit ({cost}).\nSul on nüüd **{tickets}** piletit selle päeva loosimises.\nSaldo: {balance}",
+    "max_tickets":  "❌ Maksimaalne piletite arv ühes loosimises on {cap} (sul on {held}).",
+    "empty_pot":    "🎟️ Pott on tühi - ole esimene, kes piletit ostab!",
+    # Draw announcement
+    "draw_title":   "🎟️ TipiLOTO loosimine!",
+    "draw_win":     "🎉 Võitja: {winner}\n💰 Võit: **{pot}**\n🎟️ {tickets}/{total} piletit ({chance}%)\n👥 {players} osalejat",
+    "draw_none":    "🎟️ Täna keegi pileteid ei ostnud - loosimist ei toimunud.",
+}
+
 JAILED_UI: dict[str, str] = {
     "title":      "🔒 Praegu vanglas",
     "empty":      "Kõik on vabad! Vanglas pole kedagi.",