Encrypt private media before fragmentation

localPackages/BitFoundation/Sources/BitFoundation/PeerCapabilities.swift

@@ -24,6 +24,9 @@ public struct PeerCapabilities: OptionSet, Equatable, Hashable, Sendable {
     /// (uplink/downlink carriers for mesh-only peers). Advertised alongside
     /// a `bridgeGeohash` TLV carrying the rendezvous cell.
     public static let bridge = PeerCapabilities(rawValue: 1 << 7)
+    /// Finalized direct-message media encrypted as a `.privateFile` Noise
+    /// payload before outer BLE fragmentation.
+    public static let privateMedia = PeerCapabilities(rawValue: 1 << 8)
 
     /// 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

@@ -16,11 +16,12 @@ struct PeerCapabilitiesTests {
         #expect(PeerCapabilities([]).encoded() == Data([0x00]))
         #expect(PeerCapabilities.prekeys.encoded() == Data([0x01]))
         #expect(PeerCapabilities.meshDiagnostics.encoded() == Data([0x40]))
+        #expect(PeerCapabilities.privateMedia.encoded() == Data([0x00, 0x01]))
 
         let high = PeerCapabilities(rawValue: 1 << 9)
         #expect(high.encoded() == Data([0x00, 0x02]))
 
-        let all: PeerCapabilities = [.prekeys, .wifiBulk, .gateway, .groups, .board, .vouch, .meshDiagnostics]
+        let all: PeerCapabilities = [.prekeys, .wifiBulk, .gateway, .groups, .board, .vouch, .meshDiagnostics, .privateMedia]
         #expect(PeerCapabilities(encoded: all.encoded()) == all)
         #expect(PeerCapabilities(encoded: high.encoded()) == high)
         #expect(PeerCapabilities(encoded: PeerCapabilities([]).encoded()) == [])