Address CodeRabbit review on #6799.
Decrement now decides whether to reprogram based on whether the currently
installed peer still holds references (e.peers[e.active] > 0) instead of
whether the released peer was the active one. If a prior swap's remove/add
failed, e.active was left pointing at a peer with zero references and every
later Decrement returned early, permanently stranding the prefix and leaking
the entry. The active peer is now detached only when e.active != "", and a
failed hand-off is retried on the next Decrement/Increment.
Also clear currentPeerKey unconditionally in the static handler's
RemoveAllowedIPs (matching dynamic/dnsinterceptor) and assert Increment
errors in the tests. Added self-heal tests for the failed remove/add paths.
aa4257f1ac