feat(writer): add template_mapper (ParsedTemplate -> ChapterSpec)

tests/test_phase5_template_mapper.py

@@ -0,0 +1,17 @@
+from types import SimpleNamespace
+from genesis.writer.template_mapper import map_template
+from genesis.writer.models import ChapterSpec
+
+
+def _fake_parsed():
+    ch1 = SimpleNamespace(chapter_id="intro", title="はじめに", section_placeholder="{{section:introduction}}")
+    ch2 = SimpleNamespace(chapter_id="db_design", title="DB 設計", section_placeholder=None)
+    return SimpleNamespace(chapters=[ch1, ch2])
+
+
+def test_map_template_ordered():
+    specs = map_template(_fake_parsed())
+    assert [s.chapter_id for s in specs] == ["intro", "db_design"]
+    assert specs[0].section_placeholder == "{{section:introduction}}"
+    assert specs[1].section_placeholder is None
+    assert all(isinstance(s, ChapterSpec) for s in specs)