refactor(0036a): rename Table-expanded -> NodeGroups (paperwork)

Rename masivo sin cambio de comportamiento. Habilita 0036b-f que ya
asumen la nueva convencion.

Archivos:
- tableview.{cpp,h} -> node_groups.{cpp,h} (git mv para preservar history)
- CMakeLists.txt: tableview.cpp -> node_groups.cpp

Tipos:
- TableWindowState  -> NodeGroupsWindowState  (views.h)
- TableMetadata     -> NodeGroupsMeta         (node_groups.h)
- TablePageRow      -> NodeGroupsRow          (node_groups.h)

Campos AppState:
- table_windows         -> node_groups_windows
- table_node_counts     -> node_groups_counts
- toggle_expanded_id    -> toggle_nodegroups_id
- want_toggle_expanded  -> want_toggle_nodegroups

Funciones (window por contenedor — NO el panel generico Table):
- tableview_create / count / page / smoke_test / resolve_path /
  refresh_counts / list_columns / get_metadata / set_expanded /
  set_columns / promote_row / demote_row / ingest_file
  -> prefijo node_groups_*
- views_table_window         -> views_node_groups_window
- views_table_windows_sync   -> views_node_groups_windows_sync
- views_table_overlay        -> views_node_groups_overlay

Strings de UI:
- "Expand table" / "Collapse table" -> "Open NodeGroups" / "Close NodeGroups"
- Window title "<icon> <name>" -> "<icon> NodeGroups: <name>"
- Tooltip "(no expanded tables)" -> "(no open NodeGroups)"
- Logs [tableview_*] -> [node_groups_*]

Preservados intencionalmente (no son cambio de identificadores C++):
- CLI flag --test-tableview (cambiarlo seria cambio de behavior publico)
- Valor 'tableview' en columna entities.source (cambiarlo afectaria
  datos persistidos en BD)

NO tocado:
- Panel generico Table (views_table, panel_table, table_rows,
  table_show_all, table_search_buf, table_filter_*, table_col_filters,
  table_active_tab, TableRow, table_filter_group_*, etc.)
- issues/completed/* (historia)

Verificacion:
- Build C++ Linux + Windows: green sin warnings nuevos.
- pytest WSL: 89 passed.
- pytest Windows: 78 passed + 11 skipped.
- git grep audit: solo residuos en issues/ (historia) + CLI flag y
  source DB value preservados.

Refs: issues/0036a-rename-nodegroups.md

gx-cli

@@ -429,7 +429,7 @@ def cmd_table_list(args) -> None:
 
 
 def cmd_table_promote(args) -> None:
-    """Promociona una fila DuckDB a entidad. Replica tableview_promote_row."""
+    """Promociona una fila DuckDB a entidad. Replica node_groups_promote_row."""
     cn = _connect(_ops_db())
     try:
         row = cn.execute(