feat(economy): add vanity shop and harden economy money-safety

Vanity shop (/vanity): cosmetic badges/titles as a pure whale coin sink -
purchases burn coins (not credited to the house) and equip a badge shown on
/profile. New vanity_owned/vanity_active fields, schema sync, and tests.

Money-safety and robustness fixes from a codebase review:

- _parse_amount now rejects negative amounts. Every bet/give/request flows
  through it, so a negative value can no longer mint coins on a loss/transfer
  path that trusts the caller's sign (all call sites already guarded <= 0;
  this closes the source).
- do_blackjack_payout no longer raises on a DB failure. The stake was already
  deducted in do_blackjack_bet, so it now logs critical with the owed amount
  (for admin reconciliation) and returns db_error; all payout call sites render
  a clear "payout failed" notice instead of crashing the interaction.
- Instant "kohv" consumable now cancels the pending reminder DMs for the
  cooldowns it wipes (via new INSTANT_RESET_COMMANDS), so no stale/duplicate
  reminders fire.
- Renamed the misleadingly-named _refund_user_safe -> _debit_house_safe (it
  debits the house) and dropped its ignored first arg.
- Added __all__ to vanity.py and consumables.py so `import *` no longer leaks
  incidental imports into the economy namespace.
- Documented Kõrvaklapid's +25 coin daily bonus in README and DEV_NOTES.

Tests: blackjack payout DB-failure safety and INSTANT_RESET_COMMANDS lockstep.

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

core/economy/store.py

@@ -107,6 +107,8 @@ class UserData(TypedDict, total=False):
     items: list[str]
     item_uses: dict                 # {item_id: remaining_uses} for consumables
     active_buffs: dict              # {buff_kind: expiry_iso} for timed consumable boosts
+    vanity_owned: list[str]         # cosmetic badge ids the user has purchased
+    vanity_active: str | None       # currently-equipped vanity badge id (shown on /profile)
     jailed_until: str | None       # ISO datetime or None
     jailbreak_used: bool
     reminders: list[str]           # command names user wants DM reminders for
@@ -161,6 +163,8 @@ def _default_user() -> UserData:
         "items": [],
         "item_uses": {},
         "active_buffs": {},
+        "vanity_owned": [],
+        "vanity_active": None,
         "jailed_until": None,
         "jailbreak_used": False,
         "reminders": ["daily", "work", "beg", "crime", "rob"],