feat(viz): render ImGui dod_evidence_panel (issue 0117)

Panel con header (run_id + counts) + tabla 6-col (status icon / id /
kind / expected / evidence preview / actions). Soporta 4 kinds de
evidence: screenshot (stub textual), log (5-line preview + popup),
url (xdg-open/ShellExecuteA) y cmd (diff expected vs actual).
Botones Validate/Reject invocan callbacks on_validate/on_reject.

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

cpp/functions/viz/dod_evidence_panel.h

@@ -0,0 +1,31 @@
+#pragma once
+
+// dod_evidence_panel — ImGui panel reutilizable para validar DoD evidence.
+//
+// Renderiza una tabla con items DoD (Definition of Done) + evidencias
+// adjuntas. Cada fila: icono de status, id, kind, expected, preview de
+// evidence (screenshot path / log preview / url clickable / cmd output con
+// diff vs expected), y botones Validate/Reject que invocan callbacks.
+//
+// La logica pura (contar status, buscar evidence, mapear icon/color) vive en
+// dod_evidence_panel_helpers.{h,cpp} y se testea sin ImGui.
+//
+// Uso:
+//   #include "viz/dod_evidence_panel.h"
+//   fn_viz::DodPanelState state;
+//   state.run_id = "run_abc123";
+//   state.items     = load_dod_items(...);
+//   state.evidences = load_dod_evidences(...);
+//   state.on_validate = [](const std::string& id) { db.mark_validated(id); };
+//   state.on_reject   = [](const std::string& id) { db.mark_failed(id); };
+//   fn_viz::render_dod_evidence_panel(state);
+
+#include "dod_evidence_panel_helpers.h"
+
+namespace fn_viz {
+
+// Renderiza el panel inline en el current ImGui window.
+// Debe llamarse dentro de un frame ImGui activo (entre NewFrame/Render).
+void render_dod_evidence_panel(DodPanelState& state);
+
+}  // namespace fn_viz