Extract BLE and chat architecture policies (#1324)

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchatTests/Services/BLEPacketFreshnessPolicyTests.swift

@@ -0,0 +1,44 @@
+import Foundation
+import Testing
+@testable import bitchat
+
+struct BLEPacketFreshnessPolicyTests {
+    @Test
+    func nilRecipientCountsAsBroadcast() {
+        #expect(BLEPacketFreshnessPolicy.isBroadcastRecipient(nil))
+    }
+
+    @Test
+    func allOnesEightByteRecipientCountsAsBroadcast() {
+        #expect(BLEPacketFreshnessPolicy.isBroadcastRecipient(Data(repeating: 0xFF, count: 8)))
+    }
+
+    @Test
+    func directedRecipientIsNotBroadcast() {
+        #expect(!BLEPacketFreshnessPolicy.isBroadcastRecipient(Data([0, 1, 2, 3, 4, 5, 6, 7])))
+    }
+
+    @Test
+    func recentPacketIsNotStale() {
+        let now = Date(timeIntervalSince1970: 1000)
+        let timestamp = UInt64((now.timeIntervalSince1970 - 100) * 1000)
+
+        #expect(!BLEPacketFreshnessPolicy.isStale(timestampMilliseconds: timestamp, now: now))
+    }
+
+    @Test
+    func oldPacketIsStale() {
+        let now = Date(timeIntervalSince1970: 1000)
+        let timestamp = UInt64((now.timeIntervalSince1970 - 901) * 1000)
+
+        #expect(BLEPacketFreshnessPolicy.isStale(timestampMilliseconds: timestamp, now: now))
+    }
+
+    @Test
+    func futurePacketAgeIsZero() {
+        let now = Date(timeIntervalSince1970: 1000)
+        let timestamp = UInt64((now.timeIntervalSince1970 + 10) * 1000)
+
+        #expect(BLEPacketFreshnessPolicy.ageSeconds(timestampMilliseconds: timestamp, now: now) == 0)
+    }
+}