fix: synchronize read state across web and native clients

Track readable content revisions and durable read cursors in the hub. Acknowledge only rendered foreground tails, persist offline read operations, and preserve newer manual unread choices across devices.

Migrate existing history to a read baseline and cover pagination receipts with shared native conformance fixtures.

ios/Packages/HapiKit/Sources/HapiProtocol/Models/DecryptedMessage.swift

@@ -10,6 +10,7 @@ import Foundation
 /// `content` degrades to `.null` instead of throwing.
 public struct DecryptedMessage: Codable, Equatable, Sendable {
     /// Server uuid. Optimistic rows use the client `localId` until echoed.
+    public var contentRevision: Int?
     public var id: String
     /// Per-session insert counter; `null` on optimistic rows.
     public var seq: Int?
@@ -32,6 +33,7 @@ public struct DecryptedMessage: Codable, Equatable, Sendable {
     public var deliveryState: String?
 
     public init(
+        contentRevision: Int? = nil,
         id: String,
         seq: Int? = nil,
         localId: String? = nil,
@@ -41,6 +43,7 @@ public struct DecryptedMessage: Codable, Equatable, Sendable {
         scheduledAt: Int? = nil,
         deliveryState: String? = nil
     ) {
+        self.contentRevision = contentRevision
         self.id = id
         self.seq = seq
         self.localId = localId
@@ -53,6 +56,7 @@ public struct DecryptedMessage: Codable, Equatable, Sendable {
 
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
+        contentRevision = try container.decodeIfPresent(Int.self, forKey: .contentRevision)
         id = try container.decode(String.self, forKey: .id)
         seq = try container.decodeIfPresent(Int.self, forKey: .seq)
         localId = try container.decodeIfPresent(String.self, forKey: .localId)