Reserve gas per reporter callback and combine settlement loops

[md0x]

Draft proposal stacked on #76. Replace the outer callback self-call and batch catch with one bounded loop that emits each resolution event before attempting its callback. Each Polymarket report preserves a gas reserve; when that budget is exhausted, remaining callbacks are skipped while resolution events continue. Earlier successful reports persist, and failed/skipped reports remain permissionlessly retryable.

The proposed 150,000 gas reserve needs audit validation against the production settlement return path and worst-case remaining loop costs, including call overhead. This assumes sufficient transaction gas. Events and callbacks are now interleaved, and derived reporters must bound/catch external calls in their internal resolution hook. Storage layout is unchanged.

Validation: 68 reporter tests pass, including upgrade coverage and 256 fuzz runs moving a gas-exhausting callback across the ten-ID batch with cold storage. The regression test fails on the base implementation. Changed Solidity files pass forge fmt --check; git diff --check passes.