[wave 2] core+deploy-server: preflight policy gates (chain-id assert, balance check, gas ceiling, simulate-first interlock)

[robercano]

What

Declarative safety checks that run before any transaction is sent, so mainnet mistakes are caught pre-broadcast.

Scope sketch

• @redeploy/core: a preflight phase in deploy() — assert expected chainId matches the RPC, deployer balance ≥ threshold, gas price ≤ ceiling; checks declared in the spec (per-network overridable) or passed as options. Failing check aborts with a typed error before any tx.
• deploy-server: enforce a "simulate must have passed for this spec hash" interlock for designated networks (e.g. requireSimulate: true in network config); surface preflight failures as structured SSE errors so the studio can render them.

Acceptance

Wrong chainId / underfunded deployer / stale simulate → deploy refuses with a clear, typed reason; happy path unaffected.