feat: 完善文字画视觉并新增 PDF 导出

- 调整飞鸟、楼群与标题配色和布局
- 新增 uv + Playwright PDF 导出脚本，四边各留 1em
- 页面标题改为「封面」

scripts/export_pdf.py

@@ -0,0 +1,151 @@
+"""将 index.html 导出为 PDF，画面四边各留恰好 1em。
+
+页面为 28 × 44 格文字画，1em 即一个汉字格。导出页尺寸为 30em × 46em，
+场景四周各留 1em；底色铺满整页。
+
+用法：
+    uv run python scripts/export_pdf.py
+    uv run python scripts/export_pdf.py --em 16 -o dist/luori-16.pdf
+"""
+
+from __future__ import annotations
+
+import argparse
+import pathlib
+
+from playwright.sync_api import sync_playwright
+
+ROOT = pathlib.Path(__file__).resolve().parents[1]
+HTML = ROOT / "index.html"
+
+COLS = 28
+ROWS = 44
+MARGIN_EM = 1
+
+
+def export_css(em: float) -> tuple[str, float, float]:
+    page_w = (COLS + MARGIN_EM * 2) * em
+    page_h = (ROWS + MARGIN_EM * 2) * em
+    css = f"""
+@page {{ size: {page_w:g}px {page_h:g}px; margin: 0; }}
+
+html, body {{
+  width: {page_w:g}px !important;
+  height: {page_h:g}px !important;
+  min-height: 0 !important;
+  margin: 0 !important;
+  display: block !important;
+  overflow: hidden !important;
+  background: #000 !important;
+}}
+
+body {{ padding: {em:g}px !important; }}
+
+.scene {{
+  font-size: {em:g}px !important;
+  width: {COLS}em !important;
+  height: {ROWS}em !important;
+  margin: 0 !important;
+}}
+
+* {{
+  -webkit-print-color-adjust: exact;
+  print-color-adjust: exact;
+}}
+"""
+    return css, page_w, page_h
+
+
+def launch_browser(pw):
+    for name, kwargs in (
+        ("Microsoft Edge", {"channel": "msedge"}),
+        ("Google Chrome", {"channel": "chrome"}),
+        ("Playwright Chromium", {}),
+    ):
+        try:
+            return pw.chromium.launch(**kwargs), name
+        except Exception:
+            continue
+    raise SystemExit(
+        "未找到可用浏览器。请先运行：uv run playwright install chromium"
+    )
+
+
+def export(em: float, out: pathlib.Path) -> None:
+    css, page_w, page_h = export_css(em)
+
+    with sync_playwright() as pw:
+        browser, browser_name = launch_browser(pw)
+        page = browser.new_page(
+            viewport={"width": round(page_w), "height": round(page_h)},
+            device_scale_factor=1,
+        )
+        page.goto(HTML.as_uri(), wait_until="load")
+        page.evaluate("() => document.fonts.ready")
+        if not page.evaluate("document.fonts.check('16px Zpix')"):
+            raise SystemExit("Zpix 字体未加载，无法导出。")
+
+        page.add_style_tag(content=css)
+        page.wait_for_timeout(200)
+
+        metrics = page.evaluate(
+            """() => {
+                const scene = document.querySelector('.scene').getBoundingClientRect();
+                const body = getComputedStyle(document.body);
+                return {
+                    x: scene.x, y: scene.y, w: scene.width, h: scene.height,
+                    pad: [body.paddingTop, body.paddingRight, body.paddingBottom, body.paddingLeft],
+                };
+            }"""
+        )
+        expected_pad = f"{em:g}px"
+        if (
+            abs(metrics["x"] - em) > 0.5
+            or abs(metrics["y"] - em) > 0.5
+            or abs(metrics["w"] - COLS * em) > 0.5
+            or abs(metrics["h"] - ROWS * em) > 0.5
+            or any(v != expected_pad for v in metrics["pad"])
+        ):
+            raise SystemExit(f"导出布局校验失败：{metrics}")
+
+        out.parent.mkdir(parents=True, exist_ok=True)
+        page.pdf(
+            path=str(out),
+            width=f"{page_w:g}px",
+            height=f"{page_h:g}px",
+            margin={"top": "0", "right": "0", "bottom": "0", "left": "0"},
+            print_background=True,
+            prefer_css_page_size=True,
+        )
+        browser.close()
+
+    mm_w = page_w / 96 * 25.4
+    mm_h = page_h / 96 * 25.4
+    print(f"浏览器：{browser_name}")
+    print(f"页面：{page_w:g} × {page_h:g}px（约 {mm_w:.0f} × {mm_h:.0f} mm），四边各 {em:g}px（1em）")
+    print(f"已导出：{out.relative_to(ROOT)}")
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="将文字画页面导出为 PDF（四周各留 1em）")
+    parser.add_argument(
+        "--em",
+        type=float,
+        default=24,
+        help="导出时 1em（一个汉字格）的像素大小，默认 24",
+    )
+    parser.add_argument(
+        "-o",
+        "--out",
+        type=pathlib.Path,
+        default=ROOT / "dist" / "luori.pdf",
+        help="输出文件路径，默认 dist/luori.pdf",
+    )
+    args = parser.parse_args()
+    if args.em <= 0:
+        parser.error("--em 必须大于 0")
+    export(args.em, args.out.resolve())
+
+
+if __name__ == "__main__":
+    main()