feat(table-node): DuckDB foundation + render colapsado (issue 0010)

- tableview.{h,cpp}: capa C sobre DuckDB v1.1.3.
  * tableview_smoke_test (SELECT 42).
  * tableview_count (con sql_filter opcional).
  * tableview_page (LEFT JOIN sobre ops.entities via ATTACH para flag promoted).
  * tableview_create (inserta entidad type_ref='Table' con metadata pointer).
  * tableview_refresh_counts (lee Table entities, count cada DuckDB y cachea
    por user_data hash).
  * tableview_resolve_path (rel a dirname(ops_db) o absoluto).
- AppState::table_node_counts cache, refrescado tras load_input y mutaciones.
- views_table_overlay: rectangulo redondeado overlay ("Table  N") encima
  de cada nodo type_ref='Table'. Sigue camara via cam_x/cam_y/zoom.
- main.cpp:
  * --test-duckdb <path> smoke (SELECT 42).
  * --test-tableview <path> bulk test (1M rows count + page offset).
  * Refresh de counts tras load + reload_after_mutation.
  * Llamada a views_table_overlay despues de graph_labels_draw.
- CMakeLists.txt: link DuckDB::DuckDB + duckdb_copy_runtime.

Smoke tests:
- 1M rows count + page(offset=500k, limit=10) en 0.65 s end-to-end.
- Operations.db con un nodo Table apuntando a duckdb 1M filas: refresh
  reporta correctamente "1 tables, 1000000 total rows".

CMakeLists.txt

@@ -22,6 +22,7 @@ add_imgui_app(graph_explorer
     layout_store.cpp
     entity_ops.cpp
     project_manager.cpp
+    tableview.cpp
     # --- viz ---
     ${FN_CPP_ROOT_DIR}/functions/viz/graph_renderer.cpp
     ${FN_CPP_ROOT_DIR}/functions/viz/graph_force_layout.cpp
@@ -54,7 +55,8 @@ target_include_directories(graph_explorer PRIVATE
     ${FN_CPP_ROOT_DIR}/functions
 )
 
-target_link_libraries(graph_explorer PRIVATE SQLite::SQLite3)
+target_link_libraries(graph_explorer PRIVATE SQLite::SQLite3 DuckDB::DuckDB)
+duckdb_copy_runtime(graph_explorer)
 
 # OpenGL: graph_renderer + graph_force_layout_gpu llaman gl* directamente.
 # fn::run_app inicializa el loader cuando AppConfig::init_gl_loader = true.