Mark the rotation primitives periphery:ignore

The dead-code scan correctly flagged both new types as unused, which they
intentionally are: they exist to be reviewed and argued with before the
protocol change they belong to can ship.

Annotated in place rather than added to .periphery.baseline.json so the
reason sits next to the code and disappears with it, following the
existing convention in MessageRouter. Both notes say to delete the
annotation once the mesh starts using the type.

`periphery scan --strict` locally: no unused code detected.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

localPackages/BitFoundation/Sources/BitFoundation/AnnounceV2Packet.swift

@@ -37,6 +37,9 @@ import Foundation
 /// `docs/PEER-ID-ROTATION.md`.
 ///
 /// Not emitted or consumed by the shipping mesh yet.
+// periphery:ignore - intentionally unreferenced by production code; nothing
+// emits or consumes this type yet, and BLEService parses it only to ignore it.
+// Delete this annotation when the mesh starts using it.
 public struct AnnounceV2Packet: Equatable, Sendable {
     /// Rotation epoch this announce was built for. Carried explicitly so a
     /// receiver matches against a stated epoch instead of guessing.

localPackages/BitFoundation/Sources/BitFoundation/PeerIDRotation.swift

@@ -32,6 +32,10 @@ private import CryptoKit
 /// Recognition tags come from the X25519 shared secret between two static
 /// keys, so exactly two parties can compute a given tag and an observer can
 /// compute none of them.
+// periphery:ignore - intentionally unreferenced by production code. These are
+// the reviewable primitives for a protocol change that cannot ship until both
+// platforms agree on it; wiring them into the transport is the next step, not
+// this one. Delete this annotation when the mesh starts using them.
 public enum PeerIDRotation {
     // MARK: - Parameters