docs: update status with production infrastructure sprint

docs/status.md

@@ -1,5 +1,63 @@
 # Status Log
 
+## 2026-04-01 — Production Infrastructure Sprint
+
+### Completed
+- **Error handling** — `error.rs`: Structured error types with context for all subsystems
+  - MeshError, TransportError, RoutingError, CryptoError, ProtocolError, StoreError, ConfigError
+  - ErrorContext trait for chaining errors with context
+  - Helper methods for common error construction
+
+- **Configuration** — `config.rs`: Runtime config with TOML parsing
+  - MeshConfig, IdentityConfig, AnnounceConfig, RoutingConfig, StoreConfig
+  - TransportConfig (QUIC/TCP/LoRa), CryptoConfig, RateLimitConfig, LoggingConfig
+  - Validation with meaningful error messages
+  - MeshConfig::constrained() preset for low-resource devices
+
+- **Metrics/Observability** — `metrics.rs`: Counter/Gauge/Histogram primitives
+  - Per-transport metrics (sent/received/errors/bytes)
+  - Routing metrics (table size, lookups, misses)
+  - Store metrics (stored/delivered/expired)
+  - Crypto metrics (encryptions, failures, replay detections)
+  - JSON-serializable MetricsSnapshot for export
+
+- **Rate limiting** — `rate_limit.rs`: DoS protection
+  - TokenBucket with configurable refill rate
+  - Per-peer limiters for messages, announces, KeyPackage requests
+  - DutyCycleTracker for LoRa EU868 compliance
+  - BackpressureController with priority-based shedding
+
+- **Persistence** — `persistence.rs`: Durable storage
+  - AppendLog with JSON entries and compaction
+  - PersistentRoutingTable with TTL-based expiry
+  - PersistentMessageStore for offline delivery
+  - Atomic file operations with fsync
+
+- **Graceful shutdown** — `shutdown.rs`: Coordinated termination
+  - ShutdownCoordinator with phase transitions (Draining → Persisting → Cleanup → Complete)
+  - TaskGuard RAII for tracking active tasks
+  - ConnectionDrainer for clean connection teardown
+  - ShutdownHooks for persist/cleanup callbacks
+
+- **Integration tests** — `tests/multi_node.rs`: 16 production scenarios
+  - Rate limiting per-peer isolation
+  - Store-and-forward, message dedup, GC
+  - Envelope V2 signatures, forwarding, broadcast
+  - Config validation, TOML roundtrip
+  - Shutdown coordination, concurrent access
+
+### Test Coverage
+- 189 unit tests + 16 integration tests = **205 total**
+- All passing
+
+### What's Next
+1. Wire new modules into P2pNode startup
+2. Add tracing spans for distributed tracing
+3. Health check HTTP endpoint
+4. Prometheus metrics export
+
+---
+
 ## 2026-03-31 — FAPP: Free Appointment Propagation Protocol
 
 ### Completed