fix(keyboard): stabilize Flow startup under memory pressure

Delay competing Rime work, add extension memory telemetry and stress coverage, and refresh the 1.8 release assets and metadata for build 79.

OSGKeyboardShared/Utilities/OSGDiag.swift

@@ -9,12 +9,22 @@ import Foundation
 import Darwin
 
 public enum OSGDiag {
+    public struct MemorySnapshot: Sendable, Equatable {
+        public let rssMB: Double
+        public let physFootprintMB: Double
+
+        public init(rssMB: Double, physFootprintMB: Double) {
+            self.rssMB = rssMB
+            self.physFootprintMB = physFootprintMB
+        }
+    }
+
     /// Prefix every line for easy Console search: `OSGDiag`
     public static func log(_ message: String, category: String = "diag") {
         let line = "[OSGDiag/\(category)] \(message)"
         NSLog("%@", line)
         switch category {
-        case "keyboardExt", "boot":
+        case "keyboardExt", "boot", "memory":
             OSGLog.keyboardExt.info("\(line, privacy: .public)")
         case "flow", "asr":
             OSGLog.flow.info("\(line, privacy: .public)")
@@ -40,7 +50,31 @@ public enum OSGDiag {
         return Double(info.resident_size) / 1_048_576.0
     }
 
+    /// Physical footprint in MiB. iOS jetsam tracks this more closely than RSS.
+    public static func physFootprintMB() -> Double {
+        var info = task_vm_info_data_t()
+        var count = mach_msg_type_number_t(
+            MemoryLayout<task_vm_info_data_t>.size / MemoryLayout<natural_t>.size
+        )
+        let kr = withUnsafeMutablePointer(to: &info) { ptr in
+            ptr.withMemoryRebound(to: integer_t.self, capacity: Int(count)) { rebound in
+                task_info(mach_task_self_, task_flavor_t(TASK_VM_INFO), rebound, &count)
+            }
+        }
+        guard kr == KERN_SUCCESS else { return -1 }
+        return Double(info.phys_footprint) / 1_048_576.0
+    }
+
+    public static func memorySnapshot() -> MemorySnapshot {
+        MemorySnapshot(rssMB: memoryMB(), physFootprintMB: physFootprintMB())
+    }
+
     public static func memoryTag() -> String {
-        String(format: "rss=%.1fMB", memoryMB())
+        let snapshot = memorySnapshot()
+        return String(
+            format: "rss=%.1fMB foot=%.1fMB",
+            snapshot.rssMB,
+            snapshot.physFootprintMB
+        )
     }
 }