feat: allow disabling auto-settle on merge - #5880

💭 I'm reviewing The file Looking at the Effect service conventions — this PR is just UI and settings changes, no new service definitions or moves. The changeRequestAutoSettles helper is fine as a pure function. There's a minor double-defaulting pattern with effectiveSettled checking options.autoSettleOnMerge !== false, but that's not an Effect convention issue. No Layer.succeed, ManagedRuntime.make, or .runPromise calls were introduced, so there are no findings to report.