fix(provider): honor reasoning option semantics

[rekram1-node]

Summary

• treat declared models.dev effort options as authoritative instead of falling back to heuristic variants when conversion yields no settings
• map Anthropic-compatible effort options to native output_config.effort without inventing token budgets
• preserve existing toggle and budget fallback behavior for MiniMax, Kimi, Claude, and other providers

Fixes #37418

Testing

• bun test test/provider/transform.test.ts test/provider/provider.test.ts
• bun typecheck
• git diff --check