- Add threshold_type field (fixed/percentage) to system and user settings
- Add total_recharged field to users table, auto-incremented on balance credit
- Percentage mode: effective threshold = total_recharged × percentage / 100
- User-level threshold_type inherits from system default when not set
- Update admin settings UI with radio selector (fixed amount / percentage)
- Migration: 102_add_balance_notify_threshold_type.sql
- Use per-recipient context timeout in sendEmails to prevent later
recipients from failing due to shared timeout exhaustion
- Return updated user object from RemoveNotifyEmail handler for
frontend state consistency (matching VerifyNotifyEmail pattern)
- Fix accountCost calculation in finalizePostUsageBilling to match
postUsageBilling (always multiply by AccountRateMultiplier)
- Use strings.EqualFold for email dedup in collectBalanceNotifyRecipients
- Extract CheckAccountQuotaAfterIncrement into smaller functions:
buildQuotaDims + asyncSendQuotaAlert (< 30 lines each)
- Add "not splittable" comments for HTML template functions
- Extract QuotaNotifyToggle.vue sub-component to reduce
QuotaLimitCard.vue from 404 to 339 lines
