feat(economy): add /consumables shop of repeatable, expiring boosts

The economy had many coin faucets but almost no sinks: the /shop is
one-time ownership, and gambling/rob fines route to the house (which
players drain back via jackpots and heists), so they recirculate rather
than destroy coins. Result: steady inflation.

Add a consumables shop as a true recurring sink - buying destroys the
coins and grants a temporary boost, so there's always something to spend
on after gear is maxed:

  - Energiajook XL (500) - 1h of 2x earnings on /work, /beg, /crime
  - XP jook (500)        - 1h of 2x EXP
  - Kohv (300)           - instantly clears all cooldowns

Timed buffs live in a new active_buffs field ({kind: expiry_iso}), pruned
on read; rebuying extends the timer. Effects hook where they belong:
earn_mult in income.do_work/do_beg/do_crime, exp_buff_mult in
levels.award_exp; kohv is self-contained. New /consumables command browses
the menu (with active buffs) or buys a boost. Covered by 9 tests.

Note: active_buffs is a new PocketBase field - run
scripts/sync_pb_schema.py before deploying or buffs won't persist.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

strings/economy.py

@@ -15,6 +15,8 @@ __all__ = [
     'QUEST_DESCRIPTIONS',
     'SHOP_UI',
     'ITEM_DESCRIPTIONS',
+    'CONSUMABLES_UI',
+    'CONSUMABLE_DESCRIPTIONS',
     'JAILED_UI',
     'SHOP_BTN',
     'DAILY_UI',
@@ -214,6 +216,30 @@ ITEM_DESCRIPTIONS: dict[str, str] = {
     "kalavork":          "Suurem võrk = suuremad kalad. Kõigi kalade haruldus tõuseb ühe astme võrra.",
     "echolood":          "Täpne ehholood näitab kala täpset asukohta. Haukamise aken 2s → 3s.",
 }
+
+# ---------------------------------------------------------------------------
+# Consumables  (repeatable, expiring boosts - a recurring coin sink)
+# ---------------------------------------------------------------------------
+CONSUMABLE_DESCRIPTIONS: dict[str, str] = {
+    "energy_xl": "Topeltannus kofeiini. **1 tund**: /work, /beg ja /crime teenivad **2x** rohkem.",
+    "xp_potion": "Kahtlane roheline jook. **1 tund**: kõik EXP-allikad annavad **2x** rohkem.",
+    "kohv":      "Kange kohv äratab su üles. Nullib kohe kõik ooteajad (work, beg, crime, rob, fish).",
+}
+
+CONSUMABLES_UI: dict[str, str] = {
+    "title":         "☕ Turgutused",
+    "desc":          "Ühekordsed, korduvostetavad boostid. Saldo: {bal}  ·  Osta `/consumables <ese>`",
+    "active_header": "⏳ Aktiivsed boostid",
+    "active_none":   "Ühtegi boosti pole aktiivne.",
+    "buff_line":     "{name} - veel **{time}**",
+    "kind_earn":     "⚡ 2x tulu",
+    "kind_exp":      "✨ 2x EXP",
+    "bought_title":  "{emoji} {name} ostetud!",
+    "bought_buff":   "Boost on aktiivne **{time}**.\nUus saldo: {balance}",
+    "bought_extended": "Boosti pikendati - aktiivne veel **{time}**.\nUus saldo: {balance}",
+    "bought_instant":  "☕ Kõik ooteajad nullitud!\nUus saldo: {balance}",
+}
+
 JAILED_UI: dict[str, str] = {
     "title":      "🔒 Praegu vanglas",
     "empty":      "Kõik on vabad! Vanglas pole kedagi.",