fix(clients): honor project default models in new threads - #6011

💭 This PR focuses on model selection defaults, not Effect service creation, so I'm checking whether any touched files involve Effect conventions. The use-composer-drafts.ts file uses Schema, Atom, and persistence queue patterns but no Context.Service or Layer, so there likely aren't any findings there—I'll just double-check its imports to be sure.

1. browse_code — apps/mobile/src/state/use-composer-drafts.ts

2. browse_code — apps/mobile/src/lib/modelOptions.ts

💭 This is pure client-side state code with no Effect service creation, so there aren't any violations in scope. I'm weighing a conflict: the instructions say to output exactly "All clear" when there are no findings, but the schema requires JSON output, so I need to figure out how to reconcile these by producing a success result with something like an "All clear" title.