feat(keyboard): rank pinyin by habit and persist user dictionaries

Erase dialect syllables before abbrev so wom prefers 我们, flush librime
on leave, and add a settings action to forget learned Chinese and English order.

OSGKeyboardShared/Typing/TypingHabitStore.swift

@@ -0,0 +1,18 @@
+// TypingHabitStore.swift
+// OSGKeyboard · Shared
+//
+// Cross-language "forget" for implicit typing habits. Ranking stays
+// language-specific (EnglishLearningStore vs librime userdb).
+
+import Foundation
+
+public enum TypingHabitStore {
+    /// Clears English boosts and Chinese Rime user dictionaries.
+    /// Does not touch PersonalDictionary / osg_personal.
+    public static func clearAll(
+        englishStore: EnglishLearningStore = EnglishLearningStore()
+    ) async throws {
+        englishStore.clear()
+        try await RimeResourceInstaller.shared.clearUserDictionary()
+    }
+}