Warn about perishable scalers and rental money jokers at buy time

Per-instance sticker cautions, unlike the per-joker CAUTIONS table: the
same joker is a fine buy without the sticker. Perishable debuffs a joker
for good after 5 rounds (Card:calculate_perishable, card.lua:2652), so a
perishable Ride the Bus or Hologram is investment about to be wiped --
the new SCALERS set in synergies.lua lists the jokers whose stored gains
die that way, excluding computed (Bull) and round-scoped (Hit the Road)
values and Egg, whose sell value survives a debuff. Rental charges
every round (card.lua:2647), which can eat a money joker's whole payout.

The scaler-key integrity test caught j_canio for j_caino on the first
run -- the misspelled vanilla keys strike again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

main.lua

@@ -13,6 +13,7 @@ end
 
 local data = assert(SMODS.load_file('synergies.lua'))()
 JCA.db = data.jokers
+JCA.scalers = data.scalers
 
 -- Settings from config.lua, persisted by Steamodded across sessions.
 -- Fallback defaults keep the engine usable outside the game (tests).
@@ -331,6 +332,24 @@ function JCA.is_rental(card)
     return not not (card.ability and card.ability.rental)
 end
 
+-- Sticker traps on a specific shop card, as caution strings. Per-instance,
+-- unlike JCA.cautions (which warns about the joker itself): the same joker is
+-- a fine buy without the sticker. Perishable debuffs for good after
+-- G.GAME.perishable_rounds (card.lua:2652); rental charges rental_rate ($3)
+-- every round (card.lua:2647), which can eat a money joker's whole payout.
+function JCA.sticker_cautions(card)
+    local out = {}
+    local key = card.config and card.config.center and card.config.center.key
+    local a = card.ability or {}
+    if a.perishable and key and JCA.scalers[key] then
+        out[#out + 1] = 'perishable: gains die in 5 rounds'
+    end
+    if a.rental and key and JCA.db[key] and JCA.db[key].gives.money then
+        out[#out + 1] = 'rental: rent may eat its payout'
+    end
+    return out
+end
+
 function JCA.is_perished(card)
     local a = card.ability
     return not not (a and a.perishable and (a.perish_tally or 0) <= 0)
@@ -732,6 +751,11 @@ local function tooltip_rows(card)
     end
     local caution = in_buy_area(card) and JCA.cautions[key]
     if caution then text_row('Caution: ' .. caution, G.C.RED) end
+    if in_buy_area(card) then
+        for _, warn in ipairs(JCA.sticker_cautions(card)) do
+            text_row('Caution: ' .. warn, G.C.RED)
+        end
+    end
 
     -- Copiers in the shop: a purchase always lands rightmost (see
     -- copy_source_if_bought), so say what THIS board hands the copier the