Nitro auto-import doesn't reliably pick up named exports from
db/voiceQuota.ts at runtime — speak endpoint threw 500 with
"ReferenceError: getRemainingVoiceQuota is not defined".
Explicit imports for getRemainingVoiceQuota, consumeVoiceQuota,
estimateAudioSeconds + getPlanLimits.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>