Make ordinary Noise reconnects atomic and race-safe (#1463)

Replaces destroy-then-rebuild Noise re-handshakes with an atomic reconnect protocol: prepared XX message-1 handoff tokens (claim-once, invalidated by crossed inbound initiations), receive-only quarantine of the established transport while an inbound replacement proves identity (promote on success, rollback+cooldown on failure/timeout), deterministic lower-peerID-wins crossed-initiator resolution, and a per-link-epoch BLE revalidation policy that re-proves cached sessions inside the same bleQueue critical section as the link rebind. On main, a fresh msg1 simply destroys an established session and rekey spans two non-atomic barriers.

Includes the review fix: timeout-restores defer outbound queue draining until the convergence retry completes (restore reason plumbed end-to-end), so DMs are never drained under keys a restarted peer already discarded — with a deterministic interleaving test. Identity-mismatch restores drain immediately. Full local suite 1768 tests green.

localPackages/BitFoundation/Sources/BitFoundation/PeerCapabilities.swift

@@ -28,6 +28,11 @@ public struct PeerCapabilities: OptionSet, Equatable, Hashable, Sendable {
     /// before outer BLE fragmentation. Peers that omit this bit require the
     /// signed directed raw-file migration fallback.
     public static let privateMedia = PeerCapabilities(rawValue: 1 << 8)
+    /// Reserved for test builds that briefly advertised non-destructive Noise
+    /// replacement. Current clients intentionally do not advertise or act on
+    /// this bit; keep it decodable so the wire assignment is never reused.
+    public static let nonDestructiveNoiseReplacement =
+        PeerCapabilities(rawValue: 1 << 10)
 
     /// Minimal little-endian byte encoding; always at least one byte so an
     /// empty set is distinguishable from an absent TLV.

localPackages/BitFoundation/Tests/BitFoundationTests/PeerCapabilitiesTests.swift

@@ -20,6 +20,10 @@ struct PeerCapabilitiesTests {
 
         let high = PeerCapabilities(rawValue: 1 << 9)
         #expect(high.encoded() == Data([0x00, 0x02]))
+        #expect(
+            PeerCapabilities.nonDestructiveNoiseReplacement.encoded()
+                == Data([0x00, 0x04])
+        )
 
         let all: PeerCapabilities = [.prekeys, .wifiBulk, .gateway, .groups, .board, .vouch, .meshDiagnostics, .privateMedia]
         #expect(PeerCapabilities(encoded: all.encoded()) == all)