feat: new sharing system

feat: support legacy layout import

src/lib/share/chara-file.ts

@@ -0,0 +1,15 @@
+export interface CharaFile<T extends string> {
+  charaVersion: 1
+  type: T
+}
+
+export interface CharaLayoutFile extends CharaFile<"layout"> {
+  device: "one" | "lite" | string
+  layout: [number[], number[], number[]]
+}
+
+export interface CharaChordFile extends CharaFile<"chords"> {
+  chords: [number[], number[]]
+}
+
+export type CharaFiles = CharaLayoutFile | CharaChordFile