feat(0130): kanban_cpp v2 — backend Go + 5 registry parser fns + epic/sub-issues

Registry (issue 0130a):
- 5 fns infra: parse_issue_md, write_issue_md, scan_issues_dir,
  scan_flows_dir, watch_dir_fsnotify
- 3 tipos: Issue, Flow, FsEvent
- Tests round-trip + scan reales + watcher fsnotify (all PASS)
- Capability group 'kanban' nuevo (docs/capabilities/kanban.md)

Apps:
- apps/kanban_cpp/ (sub-repo) — frontend ImGui: board drag-drop,
  flows, filters, detail con CSV editors
- apps/kanban_cpp/backend/ — Go service port 8487: REST + SSE +
  fsnotify watcher, parser bidireccional MD<->SQLite cache

Issues:
- dev/issues/0130-kanban-cpp-v2.md (epic)
- 0130a parser, 0130b backend, 0130c frontend

CMakeLists.txt: add_subdirectory apps/kanban_cpp (registrado por
init_cpp_app scaffolder).

End-to-end verde: backend devuelve 189 issues + 9 flows; PATCH a
/api/issues/{id} reescribe .md (solo frontmatter, body intacto);
frontend --self-test exit 0; tests Go infra 5/5 PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

functions/infra/testdata/issue_fixture.fixture

@@ -0,0 +1,30 @@
+---
+id: "9999"
+title: "Fixture issue con caracteres especiales: áéíóú & <test>"
+status: pendiente
+type: app
+domain:
+  - core
+  - infra
+scope: registry-only
+priority: alta
+depends:
+  - "0001"
+blocks: []
+related:
+  - "0100"
+tags: [test, fixture, round-trip]
+flow: "0001"
+created: 2026-01-01
+updated: 2026-05-22
+---
+
+# Fixture issue
+
+Este es el body del issue. Contiene caracteres especiales: áéíóú & <test>.
+
+## Sección
+
+Linea con **negrita** y _cursiva_.
+
+Final del body.