feat(cph): implement nested outline manifest and batch/combined export

ADR-0029 — nested outline manifest, supersedes ADR-0008's flat [[parts]]:
- cph-model: recursive loader over manifest.toml containers / element.toml
  leaves; Lesson.parts (pure elements, DFS order) + Lesson.outline (elements
  interleaved with section headings at their DFS-open position); rejects
  ambiguous/incomplete folders and root-vs-container table misplacement
- cph-diag: new DiagCode::ManifestMalformed for carrier-document structure
  errors (discharges an existing TODO)
- cph-typst: augmented manifest now serializes the outline (element/section
  entries) instead of a flat parts array
- render/lib.typ: render-lesson renders section headings at their depth
- examples/TH-141 migrated to 5 nested section containers + 3 root segments,
  byte-identical element order; smoke-verified via cph check/build + pdftotext

ADR-0030 — batch & combined export, extends ADR-0009/0011:
- cph build with no --target batches every declared target (repeatable
  --target for an explicit subset); any target failure => non-zero exit,
  per-target ledger, independent per-target execution
- cph-model: bundle.toml loader (directory + [info]/[targets.*]/ordered
  lessons with per-lesson target overrides)
- cph-typst: augmented bundle manifest (path-prefixed member outlines),
  Engine::{compile_check_bundle,build_bundle_pdf}
- render/lib.typ: render-bundle assembles member lessons under per-lesson
  headings, depth-shifts their own section headings, resets example/lemma
  counters at each lesson boundary by default
- cph-cli: `cph bundle <path> --target <name>` subcommand, same batching
  contract as `cph build`
- new bundle fixtures/tests (cph-model unit + cph-typst through-template PDF
  compile), smoke-verified via a real 2-lesson merged PDF

Verification: cargo fmt/clippy/test clean across the workspace (68 tests);
real cph check/build/bundle runs against TH-141 and a bundle fixture, PDF
content inspected via pdftotext.

crates/cph-typst/tests/bundle.rs

@@ -0,0 +1,122 @@
+//! Integration tests for the bundle build path (ADR-0030): compiling a bundle
+//! target's template (`exports/<target>.typ` under a `bundle.toml` root) as
+//! main, injecting the augmented **bundle** manifest, against the real
+//! `render/` package.
+
+use std::path::PathBuf;
+
+use cph_diag::Severity;
+use cph_typst::{build_augmented_bundle_manifest, Engine};
+
+fn fixture_root() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("tests/fixtures/bundle")
+}
+
+fn real_render_dir() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .join("..")
+        .join("..")
+        .join("render")
+}
+
+fn load_bundle() -> cph_model::Bundle {
+    let (bundle, diags) = cph_model::load_bundle(&fixture_root());
+    let bundle = bundle.expect("bundle fixture loads into a Bundle");
+    let errors: Vec<_> = diags
+        .iter()
+        .filter(|d| d.severity == Severity::Error)
+        .collect();
+    assert!(errors.is_empty(), "fixture has loader errors: {errors:?}");
+    bundle
+}
+
+/// PURE UNIT TEST (no fonts, no render package): the augmented bundle manifest
+/// carries the bundle's own `[info]` and an ordered `[[lessons]]`, each with
+/// that member's own `info`/`target` and a `path`-prefixed outline (ADR-0030).
+#[test]
+fn augmented_bundle_manifest_prefixes_member_paths() {
+    let bundle = load_bundle();
+    let src = build_augmented_bundle_manifest(&bundle);
+
+    assert!(
+        src.contains("测试合集"),
+        "bundle info.title present:\n{src}"
+    );
+
+    let doc: toml::Value = toml::from_str(&src).expect("augmented bundle manifest is valid TOML");
+    let lessons = doc
+        .get("lessons")
+        .and_then(|l| l.as_array())
+        .expect("lessons array present");
+    assert_eq!(lessons.len(), 2, "two member lessons:\n{src}");
+
+    // lesson-a: target defaults to its own first declared target ("student"),
+    // outline paths are prefixed with "lesson-a/".
+    let a_target = lessons[0].get("target").unwrap().as_str().unwrap();
+    assert_eq!(a_target, "student");
+    let a_outline = lessons[0].get("outline").unwrap().as_array().unwrap();
+    // segment + section heading + lemma = 3 outline entries.
+    assert_eq!(a_outline.len(), 3);
+    let a_seg_path = a_outline[0].get("path").unwrap().as_str().unwrap();
+    assert_eq!(a_seg_path, "lesson-a/segments/a");
+    let a_section_path = a_outline[1].get("path").unwrap().as_str().unwrap();
+    assert_eq!(a_section_path, "lesson-a/小节");
+    let a_lemma_path = a_outline[2].get("path").unwrap().as_str().unwrap();
+    assert_eq!(a_lemma_path, "lesson-a/小节/lemmas/引理甲");
+
+    // lesson-b: bundle.toml overrides `target = "teacher"`.
+    let b_target = lessons[1].get("target").unwrap().as_str().unwrap();
+    assert_eq!(b_target, "teacher");
+    let b_outline = lessons[1].get("outline").unwrap().as_array().unwrap();
+    assert_eq!(b_outline.len(), 1);
+    let b_seg_path = b_outline[0].get("path").unwrap().as_str().unwrap();
+    assert_eq!(b_seg_path, "lesson-b/segments/b");
+}
+
+/// THROUGH-TEMPLATE compile-check against the REAL render package: compiling
+/// the bundle's `merged` target as main with the injected augmented bundle
+/// manifest is clean.
+#[test]
+fn compile_check_clean_through_bundle_template() {
+    let bundle = load_bundle();
+    let engine = Engine::with_render_dir(real_render_dir());
+    let diags = engine.compile_check_bundle(&bundle, "merged");
+    let errors: Vec<_> = diags
+        .iter()
+        .filter(|d| d.severity == Severity::Error)
+        .collect();
+    assert!(errors.is_empty(), "unexpected compile errors: {errors:#?}");
+}
+
+/// THROUGH-TEMPLATE PDF export, fully offline: a non-trivial combined PDF is
+/// produced from the two member lessons through the real bundle template.
+#[test]
+fn build_bundle_pdf_through_template_offline() {
+    let bundle = load_bundle();
+    let engine = Engine::with_render_dir(real_render_dir());
+
+    let pdf = engine
+        .build_bundle_pdf(&bundle, "merged")
+        .unwrap_or_else(|d| panic!("bundle PDF build failed: {d:#?}"));
+    assert!(pdf.starts_with(b"%PDF"), "output is a PDF");
+    assert!(
+        pdf.len() > 1024,
+        "bundle PDF is non-trivial (got {} bytes)",
+        pdf.len()
+    );
+}
+
+/// An undeclared bundle target name is a blocking `SchemaViolation`, exactly
+/// like a lesson's own unknown-target path.
+#[test]
+fn unknown_bundle_target_is_blocking() {
+    let bundle = load_bundle();
+    let engine = Engine::with_render_dir(real_render_dir());
+    let diags = engine.compile_check_bundle(&bundle, "nonexistent");
+    assert_eq!(diags.len(), 1, "one blocking diagnostic: {diags:#?}");
+    assert_eq!(diags[0].severity, Severity::Error);
+    assert!(
+        diags[0].message.contains("not declared"),
+        "expected an undeclared-target error: {diags:#?}"
+    );
+}