fix: fund-ready scaffold — CLI-matching env names, key gate, funding pre-flight, npm run verify

[skansal-rome]

Closes the gaps a first-time builder hits between npx create-rome-app and a passing demo.

What a new dev hit before this

1. npm run demo with the seeded (unfilled) .env died in a raw viem stack trace (invalid private key, expected hex or 32 bytes, got string).
2. The docs said fund the Solana wallet with "a little SOL + USDC" — but the demo's fund leg moves 0.5 USDC, so 0.2 fails mid-run with an opaque custom program error: 0x1. And each run deploys a fresh Vault (~0.3 USDC gas) + wraps 0.15, so an EVM wallet funded with less than ~0.5 dies on its second run after spending real gas.
3. The scaffold read EVM_KEY/SOLANA_KEY while the rome CLI reads ROME_EVM_KEY/ROME_SOLANA_KEY — finishing the demo and then running rome verify meant re-exporting the same keys under different names.

Changes

• Env names match the CLI: the template now uses ROME_EVM_KEY / ROME_SOLANA_KEY everywhere. One .env, one export, both tools. (New scaffolds only — existing apps keep working as generated.)
• Key gate (lib/keys.ts): demo/deploy validate both keys before any RPC call and exit with fill-in instructions when .env still holds placeholders.
• Funding pre-flight (demo.ts): checks both wallets and prints the exact per-wallet shortfall (needs ≥ 0.7 USDC gas EVM-side, ≥ 0.6 USDC + 0.02 SOL Solana-side) before deploying, so an underfunded run costs nothing.
• npm run verify: loads .env and runs the rome CLI's verify against the app's chain — the same works-gate, straight from the scaffold; rome verify by hand behaves identically with the vars exported.
• Concrete amounts in README, .env.example, and the post-scaffold next-steps.

The new test/template-contract.test.mjs locks the contract (names, minimums stated, gate wired, verify script present).

Verification (Hadrian, 200010)

• npm test 6/6 · scaffolded app npm run typecheck clean
• unfilled .env → instructions + exit 1 (no stack trace), both demo and deploy
• valid-but-unfunded key → pre-flight lists the exact shortfall, exits before spending gas
• funded wallets → dual-lane demo passes (both lanes deposit/withdraw one Vault)
• npm run verify → {"ok": true} with both lanes answering, via the real CLI