feat(model): author 是有序列表;Info(canonical) vs RawInfo(授权 surface) 入契约

一节课可多人署名(教研组),故 canonical author 是**有序列表**而非单值。on-disk
形式接受裸字符串(单作者)或数组(多作者),但此"字符串或数组"二态**只活在加载边界**:
RawInfo 经归一化折叠成 canonical Info,其后系统只见 List。

Lean 母本(ADR-0008 范围):新增 Model/Info.lean,把 Info(canonical,authors: List
String)与 RawInfo/RawAuthor(授权便利 surface)+ 归一化 RawInfo.toInfo 钉死——
canonical 接收端恒为列表,raw 形式不泄漏。ADR-0008 [info] 块补 author-as-list 决策。

impl 对齐:cph-model Info.author: Option<String> → authors: Vec<String>;RawAuthor
untagged enum(One|Many)+ into_vec 归一化;augmented manifest 发射 author 数组
(typst document(author:) 与模板已接受 string/array)。doc 两端互引 spec。

测试:load.rs 单作者→单元素列表;target-configs fixture 加数组作者断言多作者。
验证:lake build 绿(25 jobs);cargo test 全绿;clippy 静默;TH-141(单字符串作者)
check+build PDF 无回归。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/cph-model/tests/load.rs

@@ -27,7 +27,8 @@ fn valid_two_part_lesson_loads_in_order_with_no_errors() {
     assert_eq!(lesson.project.id, "fixture-valid");
     assert_eq!(lesson.project.name, "valid-2-part");
     assert_eq!(lesson.info.title, "测试课：两个部件");
-    assert_eq!(lesson.info.author.as_deref(), Some("范式教育教研组"));
+    // A single-string `author` loads as a one-element list.
+    assert_eq!(lesson.info.authors, vec!["范式教育教研组".to_string()]);
 
     // Parts preserve declared order: segment first, lemma second.
     assert_eq!(lesson.parts.len(), 2);
@@ -149,6 +150,12 @@ fn structured_target_configs_parse_into_typed_builds() {
         "well-formed target configs must have no diagnostics, got: {diags:?}"
     );
 
+    // An array `author` loads as the ordered author list.
+    assert_eq!(
+        lesson.info.authors,
+        vec!["张老师".to_string(), "李老师".to_string()]
+    );
+
     // Declared order is preserved.
     assert_eq!(lesson.target_names(), vec!["student", "archive", "teacher"]);