Extract BLE and chat architecture policies (#1324)

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

bitchatTests/Services/BLEScheduledRelayStoreTests.swift

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+import Foundation
+import Testing
+@testable import bitchat
+
+@Suite("BLE scheduled relay store tests")
+struct BLEScheduledRelayStoreTests {
+    @Test("schedule tracks relay count and remove returns work item")
+    func scheduleAndRemove() {
+        var store = BLEScheduledRelayStore()
+        let first = DispatchWorkItem {}
+        let second = DispatchWorkItem {}
+
+        store.schedule(first, messageID: "one")
+        store.schedule(second, messageID: "two")
+
+        #expect(store.count == 2)
+        #expect(!store.isEmpty)
+        let removed = store.remove(messageID: "one")
+        #expect(removed.map { $0 === first } == true)
+        #expect(store.count == 1)
+        let missing = store.remove(messageID: "missing")
+        #expect(missing == nil)
+    }
+
+    @Test("cancel removes and cancels a scheduled relay")
+    func cancelScheduledRelay() {
+        var store = BLEScheduledRelayStore()
+        let workItem = DispatchWorkItem {}
+
+        store.schedule(workItem, messageID: "relay")
+
+        let didCancel = store.cancel(messageID: "relay")
+        #expect(didCancel)
+        #expect(workItem.isCancelled)
+        #expect(store.isEmpty)
+        let didCancelAgain = store.cancel(messageID: "relay")
+        #expect(!didCancelAgain)
+    }
+
+    @Test("cancel all cancels every scheduled relay")
+    func cancelAllScheduledRelays() {
+        var store = BLEScheduledRelayStore()
+        let first = DispatchWorkItem {}
+        let second = DispatchWorkItem {}
+
+        store.schedule(first, messageID: "first")
+        store.schedule(second, messageID: "second")
+        store.cancelAll()
+
+        #expect(first.isCancelled)
+        #expect(second.isCancelled)
+        #expect(store.isEmpty)
+    }
+
+    @Test("capacity guard only removes when over limit")
+    func capacityGuardRemovesOnlyWhenOverLimit() {
+        var store = BLEScheduledRelayStore()
+
+        store.schedule(DispatchWorkItem {}, messageID: "one")
+        store.schedule(DispatchWorkItem {}, messageID: "two")
+        store.removeAllIfOverCapacity(2)
+        #expect(store.count == 2)
+
+        store.schedule(DispatchWorkItem {}, messageID: "three")
+        store.removeAllIfOverCapacity(2)
+        #expect(store.isEmpty)
+    }
+}