DMs to unreachable peers use store-and-forward instead of failing instantly (#1415)

* DMs to unreachable peers route through store-and-forward; drop stale reachability gates

Field-found: sendPrivateMessage pre-judged reachability and marked the
message failed without ever calling the router, so the retained outbox,
courier deposits, and bridge drops never ran — a DM composed after a
peer's reachability window lapsed was dead on arrival while an identical
one sent a minute earlier delivered. Messages now always route; a live
path earns "sent", everything else stays "sending" until the router
reports carried/delivered or expires it as failed.

A sweep for sibling gates found and fixed:
- startPrivateChat refused offline non-mutual favorites ("mutual favorite
  required for offline messaging") — store-and-forward only needs the
  recipient's noise key, so the gate and its string are gone.
- markPrivateMessagesAsRead skipped the whole receipt pass for peers
  without a stored Nostr key, starving mesh-connected non-favorites; the
  router picks the transport now (sentReadReceipts dedups the parallel
  PrivateChatManager path).
- DM/geoDM blocked notices and the unknown-group error posted to the
  active public timeline; they now land in the thread they're about via
  addLocalPrivateSystemMessage.
- Banned copy: literal "user" fallbacks in code become "anon" (the
  default-nickname convention), and es/fr/it/pt translations of four keys
  still saying usuario/utilisateur/utente/usuário now say person. Orphaned
  keys removed (system.dm.unreachable, content.delivery.reason.unreachable,
  system.chat.requires_favorite).

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

* Deflake BLEServiceCoreTests: longTimeout for positive waits

CI flaked on duplicatePacket_isDeduped: the first message landed after the
5s wait expired on a loaded runner (the test's later count==1 assertions
passed, proving late delivery, not lost delivery). All four positive waits
in the file now use TestConstants.longTimeout, which exists for exactly
this — waitUntil returns as soon as the condition holds, so passing runs
never pay the longer ceiling.

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

* Fix read-receipt test contamination; baseline Periphery noiseKey flake

Two CI failures, both environmental:

- markReadReceiptSent_returnsFalseOnSecondCall flaked because every test
  ChatViewModel shared one per-process read-receipts scratch suite; the
  lifecycle test persists the same "read-1" ID (a path the receipt-gate
  removal now reaches), and test order decided who saw whose state. Each
  instance now gets its own UUID-suffixed suite.

- Periphery intermittently misses the loadFromDisk read of
  PrekeyBundleStore.StoredBundle.noiseKey and fails --strict with a false
  "assign-only" finding (recurrence of a known flake). Its USR is
  baselined; an in-source periphery:ignore can't work because strict mode
  flags it as superfluous on runs where the indexer gets it right.

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

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

bitchatTests/ChatPrivateConversationCoordinatorContextTests.swift

@@ -234,6 +234,12 @@ private final class MockChatPrivateConversationContext: ChatPrivateConversationC
         meshOnlySystemMessages.append(content)
     }
 
+    private(set) var privateSystemMessages: [(content: String, peerID: PeerID)] = []
+
+    func addLocalPrivateSystemMessage(_ content: String, to peerID: PeerID) {
+        privateSystemMessages.append((content, peerID))
+    }
+
     static let dummyIdentity = NostrIdentity(
         privateKey: Data(repeating: 0x11, count: 32),
         publicKey: Data(repeating: 0x22, count: 32),
@@ -680,19 +686,21 @@ struct ChatPrivateConversationCoordinatorContextTests {
         #expect(context.systemMessages.isEmpty)
     }
 
+    /// Field-found: pre-judging reachability here marked the message failed
+    /// without ever routing it, so the router's retained outbox, courier
+    /// deposits, and bridge drops never got a chance. A fully unreachable
+    /// non-favorite must still be routed and stay "sending" (the router's
+    /// callbacks later move it to carried/delivered or expire it as failed).
     @Test @MainActor
-    func sendPrivateMessage_failsWhenOfflineWithoutMutualFavorite() async {
+    func sendPrivateMessage_routesAndStaysSendingWhenOfflineWithoutMutualFavorite() async {
         let context = MockChatPrivateConversationContext()
         let coordinator = ChatPrivateConversationCoordinator(context: context)
         let peerID = PeerID(hexData: Data(repeating: 0xCD, count: 32))
 
         coordinator.sendPrivateMessage("hello?", to: peerID)
 
-        #expect(context.routedPrivateMessages.isEmpty)
-        #expect(context.systemMessages.count == 1)
-        guard case .failed = context.privateChats[peerID]?.first?.deliveryStatus else {
-            Issue.record("expected .failed delivery status")
-            return
-        }
+        #expect(context.routedPrivateMessages.map(\.content) == ["hello?"])
+        #expect(context.privateChats[peerID]?.first?.deliveryStatus == .sending)
+        #expect(context.systemMessages.isEmpty)
     }
 }