feat(cloudflare-workers-ai): add reasoning options

[rekram1-node]

Summary

• add live-verified reasoning option metadata for supported Cloudflare Workers AI models
• record explicit empty option sets for fixed-reasoning DeepSeek R1 Distill and QwQ endpoints
• mark Gemma and Nemotron as interleaved without adding a new shared response-field enum value

Live verification

• live-tested the included Workers AI endpoints and retained only controls accepted by each endpoint
• verified toggle and low/medium/high effort controls where declared, and effort-only controls for GPT-OSS
• confirmed fixed-reasoning endpoints do not expose a functional caller-selectable control
• observed Cloudflare reasoning output for Gemma and Nemotron while preserving compatibility with strict models.dev consumers

Verification

• bun validate
• git diff --check
• original branch test run: bun test reported 24 pass and 1 unrelated pre-existing NVIDIA weights-link assertion failure