Document hourly and first-sync sender fault counter resets

Requirements.md

@@ -28,6 +28,8 @@ Function names below are C++ references. Rust naming/layout may differ, but the
 - Time bootstrap guardrail:
   - sender must not run normal sampling/transmit until valid ACK time received.
   - accept ACK time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC`.
+  - sender fault counters reset when first valid sync is accepted.
+  - after first sync, sender fault counters reset again at each UTC hour boundary.
 - Sampling/transmit cadence:
   - sender sample cadence 1 Hz.
   - sender batch cadence 30 s.
@@ -364,6 +366,10 @@ These functions define end-to-end firmware behavior and must have equivalents:
 
 - Fault tracking/publish:
   - `note_fault`
+  - `clear_faults`
+  - `sender_reset_fault_stats`
+  - `sender_reset_fault_stats_on_first_sync`
+  - `sender_reset_fault_stats_on_hour_boundary`
   - `age_seconds`
   - `counters_changed`
   - `publish_faults_if_needed`