feat(filter): tag chips + FTS5 search en toolbar (issue 0009)

- entity_ops: entity_search_fts (bm25, prefix tokens) + entity_list_by_tags (AND).
- AppState: filter_query_buf, filter_tags, filter_mode (highlight/hide), hits cache.
- views_filter_apply: combina tipos visibles + match-set (FTS query AND tags),
  highlight = color_override con alpha=0x40, hide = clear NF_VISIBLE.
- toolbar: input search + dropdown (max 20, click centra y selecciona),
  chips de tags con boton X, input para anadir tag, combo Highlight/Hide,
  Clear filter.
- Inspector: right-click sobre tag chip lo anade al filtro.
- main.cpp: reapply en cada frame si filter_dirty; cam_x/y al focus_target.

main.cpp

@@ -552,6 +552,19 @@ static void render() {
         std::fprintf(stdout, "[graph_explorer] saved %d node positions\n", n);
         g_app.want_save_layout = false;
     }
+
+    // Filtro FTS5/tags (issue 0009) — reaplica si el toolbar marco dirty.
+    if (g_app.filter_dirty) {
+        ge::views_filter_apply(g_app);
+    }
+    // Centrado del nodo seleccionado desde el dropdown.
+    if (g_app.filter_focus_target >= 0
+        && g_app.filter_focus_target < g_graph.node_count) {
+        const GraphNode& n = g_graph.nodes[g_app.filter_focus_target];
+        g_viewport.cam_x = -n.x;
+        g_viewport.cam_y = -n.y;
+        g_app.filter_focus_target = -1;
+    }
     if (g_app.want_open_file) {
         g_input_path = g_app.open_buf;
         g_app.want_open_file = false;