feat(treasury): explain the lumpy fee accrual on the sponsorship card (#269)

Morpho VaultV2 mints the fee on vault interactions, not continuously —
Yan's figure once jumped 66x in a day when a partial withdrawal realised
about a month of accrual at once, and without the mechanism stated on
the card that reads as a bug. Two sentences, both locales: fees
materialize on interaction, can sit still for weeks then jump, and an
older small vault can carry more accrued fee than a big recent one.

Author: sktbrd

messages/en/treasury.json

@@ -107,6 +107,7 @@
     "openTitle": "Anyone can do this now",
     "openDesc": "Distributing the split and pushing the balance to the treasury are both permissionless — no vote needed. Any wallet can trigger them.",
     "govDesc": "Only converting those shares to USDC needs a proposal: the treasury is a timelock, and ERC-4626 lets nobody else redeem on its behalf.",
-    "govCta": "Start redeem proposal"
+    "govCta": "Start redeem proposal",
+    "accrualNote": "Fees materialize when someone interacts with a vault, not continuously — the figures can sit still for weeks, then jump all at once. An older small vault can carry more accrued fee than a big recent one."
   }
 }

messages/pt-br/treasury.json

@@ -107,6 +107,7 @@
     "openTitle": "Qualquer um pode fazer agora",
     "openDesc": "Distribuir o split e empurrar o saldo pro tesouro são os dois permissionless — não precisa de votação. Qualquer carteira dispara.",
     "govDesc": "Só converter essas shares em USDC exige proposta: o tesouro é um timelock, e o ERC-4626 não deixa mais ninguém resgatar no lugar dele.",
-    "govCta": "Abrir proposta de resgate"
+    "govCta": "Abrir proposta de resgate",
+    "accrualNote": "O rendimento materializa quando alguém interage com o vault, não de forma contínua — os números podem ficar parados por semanas e pular de uma vez. Um vault pequeno e antigo pode acumular mais que um grande e recente."
   }
 }

src/components/treasury/SponsorshipYield.tsx

@@ -101,6 +101,14 @@ export function SponsorshipYield() {
             {graph ? usd(treasuryShare) : "—"}
           </p>
           <p className="mt-1 text-xs text-muted-foreground">{t("desc")}</p>
+          {/* The accrual mechanism, stated because the raw numbers look wrong
+              without it: Morpho VaultV2 mints the fee on vault INTERACTIONS,
+              not continuously. Yan's figure once jumped 66x in a day (a
+              partial withdrawal realised ~a month of accrual at once), which
+              reads as a bug unless the card says it is the mechanism. */}
+          <p className="mt-2 text-[11px] leading-relaxed text-muted-foreground/70">
+            {t("accrualNote")}
+          </p>
         </div>
 
         <div>