feat(stake): rider "opportunities" chooser with live Morpheus APR

The stake dialog's ETH/USDC toggle becomes a chooser of the opportunities a
rider offers, each with its own APR:

- Morpho USDC (stable) — the existing sponsorship vault, 50/25/25 yield split.
- Morpheus stETH / Morpheus USDC (MOR) — stake on mainnet with the athlete as
  referrer; you keep the MOR, Gnars via opt-in donate. Higher, variable upside.

The Morpheus rate is a live on-chain estimate added to /api/yields:
dailyMorEmission × MOR price × 365 ÷ pool TVL (getPeriodRewards +
totalDepositedInPublicPools, MOR/ETH prices from CoinGecko), labelled
"APR · est." since MOR emissions and price move. Verified against live
on-chain data (~17.6% at time of writing).

Selecting a MOR opportunity swaps the flow to the MOR model (you keep it /
athlete referrer bonus / optional donate), shows an estimated yearly value,
a mainnet-gas warning, and routes confirm through useMorpheusStake (which
already approves the distributor). The stable vault path is unchanged. New
copy is localized in en + pt-br.

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

Author: sktbrd

messages/en/stake.json

@@ -98,6 +98,29 @@
     "claimFailTitle": "Claim failed",
     "withdrawFailTitle": "Withdraw failed"
   },
+  "opp": {
+    "choose": "What does {name} offer?",
+    "stableTag": "Stable",
+    "morTag": "MOR · variable",
+    "vaultUsdc": "Morpho USDC",
+    "morSteth": "Morpheus stETH",
+    "morUsdc": "Morpheus USDC",
+    "estNote": "≈{rate}% APR estimate — swings with the MOR price and pool size.",
+    "mainnetWarn": "Ethereum mainnet — real gas. Principal unlocks after a 7-day lock.",
+    "morHow": "How the MOR flows",
+    "youKeepMor": "You keep 100% of the MOR",
+    "athleteBonus": "{name} earns a referrer bonus (protocol-funded)",
+    "donateOpt": "Optionally donate your MOR to the split",
+    "estYearLabel": "Estimated value / year",
+    "estYearNote": "Paid in MOR on Arbitrum — a live estimate, not a guarantee.",
+    "approving": "approving…",
+    "staking": "staking on mainnet…",
+    "stakedMorTitle": "Staked with {name} on Morpheus",
+    "stakedMorDesc": "Earning MOR on Arbitrum — your principal unlocks after 7 days.",
+    "yourPosition": "Your position",
+    "principal": "principal",
+    "yield": "yield"
+  },
   "admin": {
     "title": "Sponsorship vaults",
     "desc": "One Morpho vault per rider. Deposits earn on Moonwell; half the yield becomes a fee split Gnars 25% / athlete 25% (the depositor keeps 50%). Owner = SOPA Safe. You sign the deploy and the batch — 1 of the Safe’s 2 confirmations.",

messages/pt-br/stake.json

@@ -98,6 +98,29 @@
     "claimFailTitle": "Falha ao sacar rendimento",
     "withdrawFailTitle": "Falha no saque"
   },
+  "opp": {
+    "choose": "O que {name} oferece?",
+    "stableTag": "Estável",
+    "morTag": "MOR · variável",
+    "vaultUsdc": "Morpho USDC",
+    "morSteth": "Morpheus stETH",
+    "morUsdc": "Morpheus USDC",
+    "estNote": "≈{rate}% APR estimado — varia com o preço do MOR e o tamanho do pool.",
+    "mainnetWarn": "Ethereum mainnet — gas real. O principal destrava após um lock de 7 dias.",
+    "morHow": "Como o MOR flui",
+    "youKeepMor": "Você fica com 100% do MOR",
+    "athleteBonus": "{name} ganha um bônus de indicação (pago pelo protocolo)",
+    "donateOpt": "Opcional: doe seu MOR pro split",
+    "estYearLabel": "Valor estimado / ano",
+    "estYearNote": "Pago em MOR na Arbitrum — estimativa ao vivo, não é garantia.",
+    "approving": "aprovando…",
+    "staking": "stakeando na mainnet…",
+    "stakedMorTitle": "Stake com {name} na Morpheus",
+    "stakedMorDesc": "Rendendo MOR na Arbitrum — o principal destrava após 7 dias.",
+    "yourPosition": "Sua posição",
+    "principal": "principal",
+    "yield": "rendimento"
+  },
   "admin": {
     "title": "Cofres de patrocínio",
     "desc": "Um vault Morpho por rider. Depósito rende na Moonwell; metade do rendimento vira fee dividida Gnars 25% / atleta 25% (o depositante fica com 50%). Owner = Safe da SOPA. Você assina o deploy e o batch — 1 das 2 confirmações do Safe.",