Fix Pi effort selection and live sidebar thread visibility

[isthatyousaf]

Summary

• Store Pi reasoning selector choices as thinkingLevel so the Pi adapter receives them.
• Let hot-path thread detail sync create the first sidebar summary when it observes a new running thread before the shell stream catches up.
• Add regression tests for both flows.

Testing

• bun run fmt
• cd apps/web && bun run test src/store.test.ts src/components/chat/composerProviderRegistry.test.tsx
• cd packages/shared && bun run test src/model.test.ts
• bun run lint (passes with existing warnings)
• bun run typecheck

Review focus

• Provider-specific option key mapping for Pi runtime-discovered reasoning controls.
• Sidebar summary creation only for threads without an existing shell-owned summary.