Fix OpenCode 2.0.3 transcript and mobile stream compatibility

[eivindjonassen]

Summary

• Upgrade the adapter to the generated @opencode/client 2.0.3 package.
• Accept and render idle transcript messages for succeeded, failed, and interrupted turns. Refresh the owning session's transcript on session.idle.
• Add a Promise.withResolvers fallback for mobile runtimes. The new client's event iterator otherwise throws immediately and triggers a reconnect loop.
• Add regression tests and update the API contract and compatibility documentation.

Verification

• pnpm check passed, including 68 adapter tests, 305 mobile tests, and iOS and Android Hermes exports.
• Expo Doctor passed all 18 checks.
• Published both fixes to the iOS and Android preview channels for runtime 0.1.4.
• The user confirmed restored connectivity on the physical iPhone. Android device verification and a transcript-specific device retest remain pending.