1. Always include interleaved-thinking-2025-05-14 beta header so that
thinking blocks are returned correctly for all Claude models.
2. Remove status-code guard in AMP reverse proxy ModifyResponse so that
error responses (4xx/5xx) with hidden gzip encoding are decoded
properly — prevents garbled error messages reaching the client.
3. In normalizeClaudeBudget, when the adjusted budget falls below the
model minimum, set max_tokens = budgetTokens+1 instead of leaving
the request unchanged (which causes a 400 from the API).