feat(keyboard): add clipboard history and undo pastes

Ship optional keyboard clipboard history with settings, suggestion strip, and paste-permission guidance; let undo roll back clipboard inserts; bump build to 64.

OSGKeyboardShared/Services/ClipboardHistoryPolicy.swift

@@ -0,0 +1,58 @@
+// ClipboardHistoryPolicy.swift
+// OSGKeyboard · Shared
+//
+// Pure rules for accepting clipboard text and simple English/whitespace tokens.
+
+import Foundation
+
+public enum ClipboardHistoryPolicy: Sendable {
+    public static let maxEntries = 15
+    /// Reject short all-digit strings (OTP / verification-code shaped).
+    public static let otpDigitMaxLength = 8
+
+    /// Returns trimmed text when it should be stored; otherwise `nil`.
+    public static func acceptedText(from raw: String?) -> String? {
+        guard let raw else { return nil }
+        let trimmed = raw.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !trimmed.isEmpty else { return nil }
+        if looksLikeOTP(trimmed) { return nil }
+        return trimmed
+    }
+
+    /// Pure digits (optionally with spaces/dashes) of length 4…8 → treat as OTP.
+    public static func looksLikeOTP(_ text: String) -> Bool {
+        let digits = text.filter(\.isNumber)
+        guard digits.count == text.filter({ !$0.isWhitespace && $0 != "-" }).count else {
+            return false
+        }
+        return (4...otpDigitMaxLength).contains(digits.count)
+    }
+
+    /// Simple whitespace / ASCII-punctuation split for English-ish snippets.
+    public static func whitespaceTokens(from text: String) -> [String] {
+        let separators = CharacterSet.whitespacesAndNewlines
+            .union(.punctuationCharacters)
+        return text
+            .components(separatedBy: separators)
+            .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
+            .filter { !$0.isEmpty }
+            // Skip pure CJK-only single chars that aren't useful as chips.
+            .filter { token in
+                token.count > 1 || token.unicodeScalars.contains { $0.isASCII }
+            }
+    }
+
+    /// Merge `incoming` onto `existing` (newest first), dedupe by exact text.
+    public static func merging(
+        incoming: ClipboardHistoryEntry,
+        into existing: [ClipboardHistoryEntry],
+        limit: Int = maxEntries
+    ) -> [ClipboardHistoryEntry] {
+        var next = existing.filter { $0.text != incoming.text }
+        next.insert(incoming, at: 0)
+        if next.count > limit {
+            next = Array(next.prefix(limit))
+        }
+        return next
+    }
+}