feat(keyboard): improve typing, voice flow, and polish reliability

Reduce extension memory pressure and delivery races while adding richer candidates, tactile feedback, and safer two-level creative polishing.

OSGKeyboardShared/Utilities/HostMemoryBudget.swift

@@ -0,0 +1,49 @@
+// HostMemoryBudget.swift
+// OSGKeyboard · Shared
+//
+// Shared RSS gate for host-side heavy work (Rime deploy, CLM, ASR warmup).
+// Keeps the keyboard extension alive by avoiding host jetsam spikes.
+
+import Foundation
+
+public enum HostMemoryBudget {
+    /// Soft ceiling (MiB): defer CLM / Rime / ASR when resident memory is above this.
+    /// Host SwiftUI baseline alone is often ~150–170 MB; 120 was always-trip and
+    /// left Rime/CLM permanently deferred while wrongly signaling hostHeavy.
+    public static let deferHeavyWorkAboveMB: Double = 260
+    public static let projectedPeakCeilingMB: Double = 290
+
+    public static var shouldDeferHeavyWork: Bool {
+        let rss = OSGDiag.memoryMB()
+        guard rss >= 0 else { return false }
+        return rss >= deferHeavyWorkAboveMB
+    }
+
+    public static func gate(
+        _ work: String,
+        category: String = "flow"
+    ) -> Bool {
+        let rss = OSGDiag.memoryMB()
+        let estimatedGrowth: Double
+        if work.contains("clm") {
+            estimatedGrowth = 48
+        } else if work.contains("asr") {
+            estimatedGrowth = 32
+        } else if work.contains("rime") {
+            estimatedGrowth = 24
+        } else {
+            estimatedGrowth = 24
+        }
+        if shouldDeferHeavyWork
+            || (rss >= 0 && rss + estimatedGrowth >= projectedPeakCeilingMB) {
+            OSGDiag.log(
+                "memoryGate defer work=\(work) \(OSGDiag.memoryTag()) "
+                    + "threshold=\(Int(deferHeavyWorkAboveMB))MB "
+                    + "projected=\(Int(max(0, rss + estimatedGrowth)))MB",
+                category: category
+            )
+            return false
+        }
+        return true
+    }
+}