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>

bitchat/ViewModels/ChatViewModel.swift

@@ -398,16 +398,18 @@ final class ChatViewModel: ObservableObject, BitchatDelegate, TransportEventDele
     let readReceiptsDefaults: UserDefaults
 
     /// Default read-receipt persistence store. Production uses `.standard`.
-    /// Under test, a dedicated scratch suite is used instead — wiped at first
-    /// use per process — so back-to-back local test runs never see each
-    /// other's persisted receipts (and tests never pollute `.standard`).
-    static let defaultReadReceiptsDefaults: UserDefaults = {
+    /// Under test, every instance gets its own scratch suite: a per-process
+    /// shared suite let one test's persisted receipts leak into another
+    /// test's freshly constructed view model (surfaced as an order-dependent
+    /// CI flake on a duplicated message ID), and tests never pollute
+    /// `.standard`.
+    static func defaultReadReceiptsDefaults() -> UserDefaults {
         guard TestEnvironment.isRunningTests else { return .standard }
-        let suiteName = "chat.bitchat.tests.readReceipts"
+        let suiteName = "chat.bitchat.tests.readReceipts.\(UUID().uuidString)"
         guard let scratch = UserDefaults(suiteName: suiteName) else { return .standard }
         scratch.removePersistentDomain(forName: suiteName)
         return scratch
-    }()
+    }
 
     // Track sent read receipts to avoid duplicates (persisted across launches)
     // Note: Persistence happens automatically in didSet, no lifecycle observers needed
@@ -809,7 +811,7 @@ final class ChatViewModel: ObservableObject, BitchatDelegate, TransportEventDele
         self.autocompleteService = services.autocompleteService
         self.deduplicationService = services.deduplicationService
         self.publicMessagePipeline = services.publicMessagePipeline
-        let readReceiptsDefaults = readReceiptsDefaults ?? Self.defaultReadReceiptsDefaults
+        let readReceiptsDefaults = readReceiptsDefaults ?? Self.defaultReadReceiptsDefaults()
         self.readReceiptsDefaults = readReceiptsDefaults
         self.sentReadReceipts = ChatViewModelBootstrapper.loadPersistedReadReceipts(userDefaults: readReceiptsDefaults)