Data race on `EOFOnWriteFromServerToClient` in `forwardConnection`

[perk11]

main.go:1585–1627

Two goroutines concurrently read/write the shared *bool
EOFOnWriteFromServerToClient (allocated via new(bool) by whichever finishes
first) with no synchronization. Both goroutines check == nil, then
assign the pointer and write through it; the final if *EOFOnWriteFromServerToClient
at line 1626 (after wg.Wait()) reads it from the parent goroutine.

• The go test -race run passes only because in practice both copy loops
  tend to complete-and-close in a serialized way under the test workload; it is
  not guaranteed to trigger. It is a genuine data race per the Go memory model.
• It is also pre-existing (introduced in commit 051d3048, before this
  branch), but since this branch's whole purpose is concurrency hardening it is
  worth closing now.

Fix: drop the shared-pointer pattern. wg.Wait() already happens-before
both goroutine exits, so a single bool per goroutine written before wg.Done()
and read after wg.Wait() is race-free:

var eofServerToClient bool
go func() {
    defer wg.Done()
    ... copy clientReader -> serviceConnection ...
    eofServerToClient = true   // written before wg.Done()
    serviceConnection.Close()
}()
go func() {
    defer wg.Done()
    ... copy serviceConnection -> clientConnection ...
    // eofServerToClient stays false
    clientConnection.Close()
}()
wg.Wait()
// reads after happens-before edge — safe
var reason string
if eofServerToClient { ... }