feat: PDF 导出脚本支持三页合一

逐页渲染 page1/page2/page3 并用 pypdf 合并为单个 PDF，默认输出 dist/三页demo.pdf；
--page 改为可多值的 --pages（保留旧名），每页各自校验四边 1em 与 Zpix 字体。
README 同步导出用法与各页说明。

uv.lock

@@ -94,10 +94,14 @@ version = "0.1.0"
 source = { virtual = "." }
 dependencies = [
     { name = "playwright" },
+    { name = "pypdf" },
 ]
 
 [package.metadata]
-requires-dist = [{ name = "playwright", specifier = ">=1.48" }]
+requires-dist = [
+    { name = "playwright", specifier = ">=1.48" },
+    { name = "pypdf", specifier = ">=7.0.1" },
+]
 
 [[package]]
 name = "playwright"
@@ -117,3 +121,24 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/8c/0d/32e96514b48fabd16ece31bae11afba5e18cf425123fb7c36c6b8bd8db8f/playwright-1.65.0-py3-none-win_amd64.whl", hash = "sha256:ab22611318e8747477c949c81b055ee6e224ecedf66c2a794209c7fd0210a743", size = 42664080, upload-time = "2026-11-09T21:09:54.425Z" },
     { url = "https://files.pythonhosted.org/packages/ac/d6/2a75d6eeda7b23e1b241ef898ed53bc3ea134ff52d2c959c770dce843e3c/playwright-1.65.0-py3-none-win_arm64.whl", hash = "sha256:67f0b1a80d0d2d4349f67c1ccfeceaa067f1d85aaac32d4d81dd3e971a96ddbb", size = 38367903, upload-time = "2026-11-09T21:09:58.28Z" },
 ]
+
+[[package]]
+name = "pypdf"
+version = "7.0.1"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "typing-extensions", marker = "python_full_version < '3.11'" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/00/c2/4c34b3229abae3e2fcc7809e6cf80fdea159771a37142f475fbf1009c809/pypdf-7.0.1.tar.gz", hash = "sha256:0a78bb99efb41e9088260e9a8e5da134a5cbb9a322014744177bf29b5267ea6d", size = 7206748, upload-time = "2026-11-10T11:47:22.582Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/d5/a9/ae11deef21eaac5113f8c3848da1c42423b7abeca0abc349bfec7abf4c4e/pypdf-7.0.1-py3-none-any.whl", hash = "sha256:6131b764b046282357037309e7ef2a1b7679d4a5c53eed3db2bfbf7c673ddc2b", size = 416136, upload-time = "2026-11-10T11:47:20.716Z" },
+]
+
+[[package]]
+name = "typing-extensions"
+version = "4.16.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/f6/cc/6253133b5bb138fc3306cebfbda2c520f545d36b5be2c7255cc528bb45d6/typing_extensions-4.16.0.tar.gz", hash = "sha256:dc983d19a509c94dba722ee6abd33940f7c05a89e243c47e907eb4db6f1a43e5", size = 113555, upload-time = "2026-07-02T08:40:05.92Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/49/d3/b8441a820a491ddfc024b0b0cf0393375b75ea13866d9c66727e54c2fc80/typing_extensions-4.16.0-py3-none-any.whl", hash = "sha256:481caa481374e813c1b176ada14e97f1f67a4539ce9cfeb3f350d78d6370c2e8", size = 45571, upload-time = "2026-07-02T08:40:04.659Z" },
+]