feat: tabs DAG List / Detail / Run Detail via data_table_cpp_viz (issue 0095 step 5)

- tabs.{h,cpp}: 3 paneles que renderizan TableInput con data_table::render() + RowDoubleClick events para drill-down (DAG -> Detail -> Run Detail).
- main.cpp: arranca con auto-fetch DAGs y los 3 tabs visibles por defecto. Panel Main diagnostico apagado.
- CMakeLists.txt: linka empty_state.cpp del registry.
- app.md: uses_functions completo (data_table_cpp_viz + stack TQL + empty_state). Tags: [imgui, dashboard, dag, scheduler, http, websocket].

Funcionalidades:
- DAG List: tabla con Name/Schedule/Last Status/Tags/Valid/File. Status combina last_run (REST) + live_runs (WS). Double-click selecciona DAG.
- DAG Detail: header + Run Now (POST /api/dags/{name}/run) + tabla recent runs. Double-click run abre Run Detail.
- Run Detail: header del run + tabla steps (name/status/exit/duration/started) + CollapsingHeader por step con stdout/stderr.

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

app.md

@@ -3,21 +3,21 @@ name: dag_engine_ui
 lang: cpp
 domain: tools
 description: "Frontend ImGui para dag_engine. Lista, lanza e inspecciona DAGs con live updates via WS."
-tags: [imgui]
+tags: [imgui, dashboard, dag, scheduler, http, websocket]
 uses_functions:
-  # Uncomment when using data_table::render() — provided via fn_table_viz:
-  # - data_table_cpp_viz
-  # - viz_render_cpp_viz
-  # - compute_stage_cpp_core
-  # - compute_pipeline_cpp_core
-  # - compute_column_stats_cpp_core
-  # - auto_detect_type_cpp_core
-  # - tql_emit_cpp_core
-  # - tql_apply_cpp_core
-  # - lua_engine_cpp_core
-  # - join_tables_cpp_core
-  # - tql_to_sql_cpp_core
-  # - llm_anthropic_cpp_core
+  - data_table_cpp_viz
+  - viz_render_cpp_viz
+  - compute_stage_cpp_core
+  - compute_pipeline_cpp_core
+  - compute_column_stats_cpp_core
+  - auto_detect_type_cpp_core
+  - tql_emit_cpp_core
+  - tql_apply_cpp_core
+  - lua_engine_cpp_core
+  - join_tables_cpp_core
+  - tql_to_sql_cpp_core
+  - llm_anthropic_cpp_core
+  - empty_state_cpp_core
 uses_types: []
 framework: "imgui"
 entry_point: "main.cpp"