fix(p2p): replace unsynchronized dialing counter with atomic int32

[amathxbt]

Bug

In p2p/p2p.go, DialForOutboundPeers() tracks in-flight dial attempts with a plain int:

dialing := 0
// ...
go func() {
    dialing++  // ← written from goroutine, read from main loop — data race
    p.DialWithBackoff(peerAddress, true)
}()

The counter is incremented inside spawned goroutines while the main loop reads it concurrently — with no mutex or atomic protection. This is a data race confirmed by go test -race.

Result: the node can significantly exceed MaxOutbound peers, opening unnecessary connections, wasting bandwidth, and destabilising the network layer.

Fix

Replace dialing int with var dialing int32 and use atomic.AddInt32 / atomic.LoadInt32 at every read and write site.

Impact

Critical — data race in the P2P layer causes unbounded outbound connections.

[andrewnguyen22]

The finding is real dialing is accessed from multiple goroutines in p2p.go.

This is directionally correct - but the PR is incomplete:

1. It still reads p.PeerSet.outbound directly without the PeerSet lock at p2p/p2p.go:221, while outbound is written under peer-set mutation paths. That leaves a data race.

2. The initial configured DialPeers goroutines increment dialing but never decrement it after DialWithBackoff returns. The PR preserves that bug, just with atomics. That can make the later outbound loop permanently think dials are still in flight.

[amathxbt]

Thanks for the thorough review @andrewnguyen22 — both points are valid. Updated the branch with:

1. Missing dialing decrement — added atomic.AddInt32(&dialing, -1) at the end of each initial DialPeers goroutine, mirroring the defer decrement already used in the outbound capacity loop. Without this the counter stays permanently elevated after the configured peers connect, blocking all future outbound dials.

2. p.PeerSet.outbound read without lock — wrapped the read at line 222 in p.PeerSet.mux.RLock() / RUnlock(), consistent with how outbound is guarded elsewhere in the peer-set paths.