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.

examples/TH-141/σTp态函数建模/lemmas/Eötvös规则/element.toml

@@ -0,0 +1 @@
+kind = "lemma"

examples/TH-141/σTp态函数建模/lemmas/Eötvös规则/stmt.typ

@@ -0,0 +1,5 @@
+设液体的摩尔体积为 $V_m$、临界温度为 $T_c$，则其表面张力随温度的标度律为
+
+$ sigma thin V_m^(2\/3) = k (T_c - T) , $ <Eötvös规则>
+
+其中 $k approx 2.1 times 10^(-7) thin "J" dot "K"^(-1) dot "mol"^(-2\/3)$ 是一个对所有液体共用的普适常数，称为 Eötvös 常数。

examples/TH-141/σTp态函数建模/lemmas/Guggenheim-Katayama改良/element.toml

@@ -0,0 +1 @@
+kind = "lemma"

examples/TH-141/σTp态函数建模/lemmas/Guggenheim-Katayama改良/stmt.typ

@@ -0,0 +1,5 @@
+Eötvös 规则 @Eötvös规则 在 $T arrow.r T_c$ 附近预言 $sigma prop (T_c - T)$ 线性趋零。实验观测显示趋零行为更接近幂律：
+
+$ sigma = sigma_0 (1 - T \/ T_c)^n , quad n approx 11 \/ 9 . $ <GK规则>
+
+@GK规则 在临界点附近比 @Eötvös规则 更准确。

examples/TH-141/σTp态函数建模/lemmas/表面熵热力学关系/element.toml

@@ -0,0 +1 @@
+kind = "lemma"

examples/TH-141/σTp态函数建模/lemmas/表面熵热力学关系/proof.typ

@@ -0,0 +1,11 @@
+$sigma$ 的热力学定义是恒温恒容下单位面积自由能：$sigma = (partial F \/ partial A)_(T, V)$。自由能微分
+
+$ dif F = - S dif T - p dif V + sigma dif A , $
+
+给出 Maxwell 关系
+
+$ ((partial sigma) / (partial T))_(A, V) = - ((partial S) / (partial A))_(T, V) = - s_s , $
+
+其中 $s_s equiv (partial S \/ partial A)_(T, V)$。代回即 @表面熵。
+
+液面分子被约束在准二维层内，可达微观态数比体相分子少，故 $s_s > 0$，进而 $dif sigma \/ dif T < 0$。

examples/TH-141/σTp态函数建模/lemmas/表面熵热力学关系/stmt.typ

@@ -0,0 +1,5 @@
+设单位面积表面熵为 $s_s$，则表面张力对温度的变化率满足
+
+$ (dif sigma) / (dif T) = - s_s . $ <表面熵>
+
+物理上 $s_s > 0$，故 $dif sigma \/ dif T < 0$，$sigma$ 随温度升高单调下降。