Fix Poolside auth and model addressing

[grikomsn]

Summary

• let OpenCode store API keys through its built-in API auth flow
• expose short OpenCode model aliases while preserving Poolside upstream IDs
• send documented Poolside reasoning options and fix cache-write pricing
• correct package entry points, lockfile/versioning, release docs, and tarball checks

Verification

• npm run check
• npm run package
• OpenCode 1.18.4 integration against a local mock endpoint verified stored auth, poolside/laguna-m.1, and reasoning.effort