fix(raft): fix election and network issues in raft event loop

[slow2342]

Summary

• Replace spin-based ticking with Instant-based accurate timing to prevent tick drift
• Reorder ready processing to send leader messages before persisting entries (raft-rs best practice)
• Fix heartbeat interval from 100ms to 200ms and set max_committed_size_per_ready
• Add tracing for raft messages, proposals, and leader state transitions
• Improve network sender error handling to distinguish RPC errors from task panics
• Fix long line formatting in tracing macros

Changes

• src/raft/node.rs — Rewrite tick logic using Instant for accurate timing, reorder ready processing steps, add structured tracing, fix formatting
• src/raft/network.rs — Improve error handling in network sender
• src/raft/rpc.rs — Add tracing for incoming RPCs
• src/raft/raftrs_store.rs — Minor fix
• src/main.rs — Minor adjustment

How to verify

cargo build
cargo test --all-targets
cargo clippy --all-targets -- -D warnings