feat(sync): Phase 3 - resilience and health tracking

- Add RelayHealthTracker with DashMap
- Implement exponential backoff (5s -> 1h max)
- Handle dead relays (24h failures -> daily retry)
- Add startup jitter to prevent thundering herd
- Add NGIT_SYNC_MAX_BACKOFF_SECS config

1 files changed, 3 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 80fa317..911f5e7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,6 +33,9 @@ prometheus = "0.13"
 dashmap = "5"
 lazy_static = "1.4"
 
+# Random (for startup jitter)
+rand = "0.8"
+
 # Serialization
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"