fork(fix): Clone AMLL 并修复 BUG

- 将AMLL Clone到本以地进行修复和优化(emm虽然这很不优雅但是暂时无时间做子模块和Fork)
- 修复在当前播放歌词行不可见的视口Seek会出现滚动偏移的问题

amll-local/packages/lyric/test/yrc.test.ts

@@ -0,0 +1,134 @@
+import { describe, expect, it } from "vitest";
+import { parseYrc, stringifyYrc } from "../src/formats/yrc";
+
+describe("yrc", () => {
+	it("parses basic word-timestamped line", () => {
+		const lines = parseYrc(
+			"[1000,1000](1000,500,0)Hello(1500,500,0)World\n[3000,1000](3000,1000,0)Again",
+		);
+
+		expect(lines).toHaveLength(2);
+		expect(lines[0].startTime).toBe(1000);
+		expect(lines[0].endTime).toBe(2000);
+		expect(lines[0].words[0].word).toBe("Hello");
+		expect(lines[0].words[0].startTime).toBe(1000);
+		expect(lines[0].words[0].endTime).toBe(1500);
+		expect(lines[0].words[1].word).toBe("World");
+		expect(lines[0].words[1].startTime).toBe(1500);
+		expect(lines[0].words[1].endTime).toBe(2000);
+		expect(lines[1].words[0].word).toBe("Again");
+	});
+
+	it("handles CRLF and ignores lines without valid line timestamp", () => {
+		const lines = parseYrc(
+			"no timestamp\r\n[invalid,100](0,100,0)Bad\r\n[-1,100](0,100,0)Bad\r\n[1000,1000](1000,1000,0)Hello",
+		);
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].startTime).toBe(1000);
+		expect(lines[0].endTime).toBe(2000);
+		expect(lines[0].words[0].word).toBe("Hello");
+	});
+
+	it("ignores empty lines and lines with only whitespace", () => {
+		const lines = parseYrc(
+			"[0,20]   \n[0,20]\n[0,20](10,10,0)Test\n   \n\n[0,20]   \n",
+		);
+		expect(lines).toHaveLength(1);
+		expect(lines[0].words[0].word).toBe("Test");
+	});
+
+	it("stringifies words and preserves spaces", () => {
+		const result = stringifyYrc([
+			{
+				startTime: 1000,
+				endTime: 3000,
+				words: [
+					{ startTime: 1000, endTime: 2000, word: "Hello", romanWord: "" },
+					{ startTime: 0, endTime: 0, word: " ", romanWord: "" },
+					{ startTime: 2000, endTime: 3000, word: "World", romanWord: "" },
+				],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: false,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[1000,2000](1000,1000,0)Hello (2000,1000,0)World");
+	});
+
+	it("stringifies bg lines with full-width wrapping parentheses", () => {
+		const result = stringifyYrc([
+			{
+				startTime: 1000,
+				endTime: 2000,
+				words: [
+					{ startTime: 1000, endTime: 2000, word: "Hello", romanWord: "" },
+				],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: true,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[1000,1000](1000,1000,0)（Hello）");
+	});
+
+	it("parses and keeps bg wrapper lines stable", () => {
+		const input = "[1000,1000](1000,1000,0)（Hello, (2000,2000,0)world）";
+		const lines = parseYrc(input);
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].isBG).toBe(true);
+		expect(lines[0].words).toHaveLength(2);
+		expect(lines[0].words[0].word).toBe("Hello, ");
+		expect(lines[0].words[1].word).toBe("world");
+		expect(stringifyYrc(lines)).toBe(input);
+	});
+
+	it("keeps parenthesized fragments in plain word text", () => {
+		const lines = parseYrc("[0,20](0,10,0)A(x)(10,10,0) B");
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].words.map((w) => w.word)).toEqual(["A(x)", " B"]);
+		expect(lines[0].words[0].startTime).toBe(0);
+		expect(lines[0].words[0].endTime).toBe(10);
+		expect(lines[0].words[1].startTime).toBe(10);
+		expect(lines[0].words[1].endTime).toBe(20);
+	});
+
+	it("normalizes invalid timestamps when stringifying", () => {
+		const result = stringifyYrc([
+			{
+				startTime: Number.NaN,
+				endTime: Number.POSITIVE_INFINITY,
+				words: [
+					{
+						startTime: -1,
+						endTime: Number.POSITIVE_INFINITY,
+						word: "Hello",
+						romanWord: "",
+					},
+				],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: false,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[0,0](0,0,0)Hello");
+	});
+
+	it("keeps parse -> stringify -> parse stable for content and timing", () => {
+		const input =
+			"[1000,1000](1000,500,0)Hello (1500,500,0)World\n[3000,1000](3000,1000,0)Again";
+		const first = parseYrc(input);
+		const text = stringifyYrc(first);
+		const second = parseYrc(text);
+
+		expect(second).toEqual(first);
+	});
+});