perf(xmpp): fix slow MAM/MUC-MAM and move OMEMO decryption off the main

thread

- Replace O(n^2) origin-id/stanza-id lookups in AppModel with hash
  indexes
  and stop rebuilding the whole index on every unseen stanza-id, so
  archive
  application no longer grows quadratically with history size.
- Run OMEMO decryption on a serial background queue instead of the main
  actor, and decrypt archived stanzas in small batches with a shorter
  yield,
  keeping the UI responsive during large archive catch-ups.
- Show the "Синхронизация истории…" banner only for the one-page
  bootstrap
  window; incremental backlog catch-up continues silently in the
  background.
- Fix MUC-MAM: publish decoded group mutations at the end of room
  catch-up;
  they were previously accumulated and then silently dropped.
- Retry a failed catch-up pass automatically (bounded) and lengthen the
  query/apply timeouts so a single slow page no longer leaves history
  unloaded until the next app activation.

Sources/Shared/Models/ArchiveSyncRecoveryPolicy.swift

@@ -5,8 +5,15 @@ import Foundation
 enum ArchiveSyncRecoveryPolicy {
     static let incrementalOverlap: TimeInterval = 60
     static let interPageDelayNanoseconds: UInt64 = 100_000_000
-    static let queryTimeoutNanoseconds: UInt64 = 12_000_000_000
-    static let pageApplyTimeoutNanoseconds: UInt64 = 8_000_000_000
+    static let queryTimeoutNanoseconds: UInt64 = 20_000_000_000
+    static let pageApplyTimeoutNanoseconds: UInt64 = 20_000_000_000
     static let pageRetryLimit = 1
     static let resumeAfterCaptureDelayNanoseconds: UInt64 = 3_000_000_000
+    /// Delay before automatically resuming a failed catch-up pass while the
+    /// app stays connected and foregrounded. Prevents a single slow page from
+    /// silently leaving history unloaded until the next app activation.
+    static let retryAfterFailureDelayNanoseconds: UInt64 = 20_000_000_000
+    /// Consecutive automatic catch-up retries before falling back to
+    /// resume-on-activation, so a persistently broken server cannot loop.
+    static let maximumAutomaticRetries = 3
 }