fix(config): require multiRewardDistributor for EVM comptroller chains

[bprofiro]

Summary

Closes the root cause behind MOO-413 / #306: the contracts config typed multiRewardDistributor? as optional, so an EVM comptroller chain could omit it with no compile error — which is exactly how Ethereum shipped without it and silently broke the frontend reward-claim flow (it falls back to the Moonbeam 0x…0808 precompile path, which reverts).

⚠️ Stacked on #306 (base = brenda/moo-413-…). This change requires Ethereum's MRD to already be present, so it must merge after #306. Retarget to main once #306 lands.

Change

createContractsConfig now intersects a conditional constraint onto its input:

type RequireMultiRewardDistributor<contracts> = contracts extends { comptroller: Address }
  ? contracts extends { governor: Address }
    ? unknown                              // Moonbeam/Moonriver: WELL precompile model, no MRD
    : { multiRewardDistributor: Address }  // EVM comptroller chain: MRD required
  : unknown;                               // no comptroller: not a lending env

Discriminator: comptroller present + governor absent ⟹ EVM comptroller chain ⟹ MRD required. Verified against all 8 definitions: Base/Optimism/Ethereum (require, and have it); Moonbeam/Moonriver (have governor → exempt); arbitrum/avalanche/polygon (no comptroller → exempt).

Verification

• pnpm typecheck passes for all 8 current definitions.
• Proof it catches the regression: removing MRD from ethereum/contracts.ts now produces error TS2741: Property 'multiRewardDistributor' is missing.
• Moonbeam/Moonriver and the non-comptroller chains still compile.
• Full suite: 552 pass (34 files). Quality gate: PASS.

Tests added

• src/environments/contracts-invariants.test.ts — runtime backstop iterating publicEnvironments: asserts every EVM comptroller env (comptroller, no governor) has a valid multiRewardDistributor.address. Covers envs built outside the factory and any as-cast bypass. Registered in the vitest include list.

Reviewer notes (triaged)

• A type-design review flagged a possible governor: undefined bypass (🟡). Verified not reproducible under this repo's exactOptionalPropertyTypes: true — governor: undefined is itself a compile error (TS2375), so it can't take the exempt branch. No code change made (guarding an impossible case would add noise).
• The governor-presence discriminator is a structural proxy for "Moonbeam-family home chain." Sound for all current/foreseeable chains; if a future chain breaks the heuristic, an explicit kind tag would be the more durable design. Noted as a future option, not done now (disproportionate to this fix).

Semver

Marked minor (breaking) per the repo's breaking-change hook: direct callers of the exported createContractsConfig that omit MRD on an EVM comptroller config will no longer compile. Internal definitions are all updated/valid.

[bprofiro]

Closing — not needed. The fix lives entirely in #306 (adds Ethereum's multiRewardDistributor, with an env test locking it). Making the config type require MRD is a breaking change to createContractsConfig that isn't necessary to solve MOO-413.