feat(examples): migrate TH-141 sample to declarative layout (WU-6)

Real-content fixture for the end-to-end pipeline. TH-141 (39 parts: 22 segment,
15 lemma, 2 example) migrated from the prototype's typst `#let parts` manifest
to ADR-0008: declarative manifest.toml (project+info+ordered parts+targets) +
per-element element.toml (kind + scalars; examples carry `source`). Content .typ
files copied byte-identical (no math corruption); per-element main.typ + meta.toml
dropped (wiring is now generated). Part order matches source exactly; 5 lemmas
have no proof.typ (optional); no cross-file imports / paralearn refs / figs.

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

examples/TH-141/segments/浸润全谱与高低能表面/element.toml

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

examples/TH-141/segments/浸润全谱与高低能表面/textbook.typ

@@ -0,0 +1,17 @@
+由 @GGZ判据 按 $r equiv gamma_(S G) \/ gamma_(L G)$ 切段：
+
+#figure(
+  table(
+    columns: (auto, auto, auto),
+    align: (left, left, left),
+    table.header[*比值范围*][*接触角*][*现象*],
+    [$r > 1$], [无解], [完全铺展（superwetting）],
+    [$r = 1$], [$theta = 0$], [临界完全浸润],
+    [$1\/4 < r < 1$], [$0 < theta < pi\/2$], [部分浸润],
+    [$r = 1\/4$], [$theta = pi\/2$], [临界不浸润],
+    [$r < 1\/4$], [$theta > pi\/2$], [不浸润、成珠状],
+  ),
+  caption: [浸润全谱]
+) <浸润全谱表>
+
+把 @γ量级表 与浸润全谱并置就得到日常现象的解释。高能表面如金属、清洁玻璃，$gamma_(S G) tilde.op 1 thin "J/m"^2$，远大于水的 $gamma_(L G) tilde.op 0.072 thin "J/m"^2$，$r >> 1$，水在其上完全铺展。低能表面如石蜡、Teflon，$gamma_(S G) tilde.op 0.02 thin "J/m"^2$ 小于水的 $gamma_(L G)$，$r < 1\/4$，水在其上不浸润、成珠状。"水在玻璃上铺、在荷叶上成珠"这两件日常现象就是 $r$ 取值在 @GGZ判据 中位于 $r >> 1$ 与 $r < 1\/4$ 两端的直接体现。