Add AI debug logging and switch from fetch to https module

- Add toggle-able debug logging (AI_DEBUG env var) that logs prompts,
  request metadata, raw responses, parsed output, and full error chains
- Replace Node.js native fetch() with https module for Docker Alpine
  compatibility (fixes "fetch failed" error with large payloads)
- Reduce max_tokens from 16384 to 4096 (qwen3.5 doesn't need thinking
  token budget)
- Strip <think> blocks from model responses
- Add AI_DEBUG to docker-compose.yml and .env.example

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.env.example

@@ -10,3 +10,5 @@ NODE_ENV=development
 AI_API_URL=https://integrate.api.nvidia.com/v1
 AI_API_KEY=your_nvidia_api_key_here
 AI_MODEL=qwen/qwen3.5-397b-a17b
+# Set to 'true' to enable detailed AI prompt/response logging
+AI_DEBUG=false