[refactor] extract local state package, fix gossip dual-CRDS identity transition, compact and enrich log output

[coderigo]

• Gossip state logging: peer state string (🟢 (us) london 185.26.11.91 | 🟡 chicago ...) now logs only on change (dedup via lastLoggedPeersState); emoji legend printed once automatically on first Refresh() instead of being an explicit public call
• (us) annotation: gossip peerInfo now carries isSelf bool set at build time from SelfIP; fixed missing SelfIP wire-up in gossip.Options so (us) actually appears in the state string
• Local state tracker: extracted into internal/local package with its own poll interval (default: 2s), decoupled from the gossip poll loop; logs on every health state transition including startup ("waiting for 45s healthy streak before eligible for failover")
• Startup health visibility: removed !firstSample suppression so the "waiting for minimum duration" log fires at startup and after any unhealthy period symmetrically; removed now-dead sampledOnce field
• checkForActivePeer() removed: redundant after gossip state string already captures active/passive/us on every change
• delinquent_slot_distance_override warnings: added startup warning when override value is below 128 (Agave default), recommending --health-check-slot-distance <value> on the validator to keep thresholds aligned; corrected stale README note that health check default was 150 (it was aligned to 128 in Agave v2.0 via the same DELINQUENT_VALIDATOR_SLOT_DISTANCE constant); added source URLs for both rpc-client-types/src/request.rs and validator/src/commands/run/args/json_rpc_config.rs
• Removed stale manager.go warning block that incorrectly flagged override values above 128 (opposite direction) and cited the outdated 150 default