feat(projects): integrate project switcher in app shell + Inspector menu

main.cpp:
- Forward decl + switch_to_project: cierra layout_store, libera grafo,
  aplica nuevos paths, vuelve a cargar.
- apply_project_paths: deriva operations.db/types.yaml/graph_explorer.db
  del slug y los expone a g_app.active_project.
- main: arg --project <slug>; modo legacy si --input/positional dado;
  modo proyecto si no — migra layout legacy, decide target via
  arg/last_active/'default', crea si no existe, abre BDs y carga.
- render(): handler want_switch_project + monta views_new_project_modal.

views.h: AppState gana active_project, want_switch_project,
switch_project_target, show_new_project_modal, new_project_buf,
new_project_error, project_list_cache, project_recent_cache.

views.cpp:
- Toolbar: boton 'Project: <slug>' con popup (New/Recent/Open/Reveal).
  Refresca caches al abrir el menu.
- views_new_project_modal: input slug + validacion + creacion + switch.

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

views.cpp

@@ -1,5 +1,6 @@
 #include "views.h"
 #include "entity_ops.h"
+#include "project_manager.h"
 
 #include "viz/graph_types.h"
 #include "viz/graph_viewport.h"
@@ -91,6 +92,74 @@ void views_apply_visibility(AppState& app) {
 void views_toolbar(AppState& app) {
     using namespace fn_ui;
     toolbar_begin();
+        // Project switcher — etiqueta = proyecto activo. Click abre popup con
+        // New / Open / Recent / Reveal. Si no hay proyecto activo (modo
+        // legacy con --input directo), muestra "(no project)".
+        {
+            char btn_label[128];
+            const char* p = app.active_project.empty()
+                                ? "(no project)" : app.active_project.c_str();
+            std::snprintf(btn_label, sizeof(btn_label), TI_FOLDER " Project: %s", p);
+            if (button(btn_label, ButtonVariant::Secondary)) {
+                // Refresca caches al abrir
+                project_list(&app.project_list_cache);
+                ProjectSettings ps;
+                project_settings_load(&ps);
+                app.project_recent_cache = ps.recent;
+                ImGui::OpenPopup("##project_menu");
+            }
+            if (ImGui::BeginPopup("##project_menu")) {
+                if (ImGui::MenuItem(TI_PLUS " New project...")) {
+                    app.show_new_project_modal = true;
+                    app.new_project_buf[0] = 0;
+                    app.new_project_error.clear();
+                }
+                ImGui::Separator();
+
+                // Recent submenu
+                if (!app.project_recent_cache.empty()) {
+                    if (ImGui::BeginMenu("Recent")) {
+                        for (const auto& slug : app.project_recent_cache) {
+                            bool is_active = (slug == app.active_project);
+                            if (ImGui::MenuItem(slug.c_str(), nullptr, is_active)
+                                && !is_active) {
+                                app.want_switch_project = true;
+                                app.switch_project_target = slug;
+                            }
+                        }
+                        ImGui::EndMenu();
+                    }
+                }
+
+                // Open submenu — todos los detectados
+                if (ImGui::BeginMenu("Open")) {
+                    if (app.project_list_cache.empty()) {
+                        ImGui::TextDisabled("(no projects yet)");
+                    } else {
+                        for (const auto& slug : app.project_list_cache) {
+                            bool is_active = (slug == app.active_project);
+                            if (ImGui::MenuItem(slug.c_str(), nullptr, is_active)
+                                && !is_active) {
+                                app.want_switch_project = true;
+                                app.switch_project_target = slug;
+                            }
+                        }
+                    }
+                    ImGui::EndMenu();
+                }
+
+                ImGui::Separator();
+                bool can_reveal = !app.active_project.empty();
+                if (ImGui::MenuItem(TI_FOLDER_OPEN " Reveal in explorer",
+                                     nullptr, false, can_reveal)) {
+                    project_reveal_in_explorer(app.active_project.c_str());
+                }
+                ImGui::EndPopup();
+            }
+        }
+        ImGui::SameLine();
+        toolbar_separator();
+
         if (button(TI_FOLDER " Open file...", ButtonVariant::Secondary)) {
             app.show_open_modal = true;
         }
@@ -490,6 +559,58 @@ bool views_filters_modal(AppState& app) {
     return changed;
 }
 
+// ----------------------------------------------------------------------------
+// Modal: New project
+// ----------------------------------------------------------------------------
+
+bool views_new_project_modal(AppState& app) {
+    if (!app.show_new_project_modal) return false;
+    bool created = false;
+    if (fn_ui::modal_dialog_begin("New project", &app.show_new_project_modal,
+                                   ImVec2(480, 0))) {
+        ImGui::TextWrapped(
+            "Crea una subcarpeta en projects/ con su propio operations.db,"
+            " types.yaml y graph_explorer.db.");
+        ImGui::Spacing();
+        fn_ui::text_input("Slug", app.new_project_buf, sizeof(app.new_project_buf),
+                          "caso_aurgi");
+        ImGui::TextDisabled("a-z, 0-9, '_' y '-' (max 64)");
+
+        if (!app.new_project_error.empty()) {
+            ImGui::Spacing();
+            ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 0.5f, 0.4f, 1.0f));
+            ImGui::TextWrapped("%s", app.new_project_error.c_str());
+            ImGui::PopStyleColor();
+        }
+
+        ImGui::Spacing();
+        if (fn_ui::button("Create", fn_ui::ButtonVariant::Primary)) {
+            std::string err;
+            if (!project_validate_slug(app.new_project_buf, &err)) {
+                app.new_project_error = err;
+            } else if (project_exists(app.new_project_buf)) {
+                app.new_project_error = "ya existe un proyecto con ese slug";
+            } else if (!project_create(app.new_project_buf, &err)) {
+                app.new_project_error = err;
+            } else {
+                // Switch al recien creado
+                app.want_switch_project = true;
+                app.switch_project_target = app.new_project_buf;
+                app.show_new_project_modal = false;
+                app.new_project_error.clear();
+                created = true;
+            }
+        }
+        ImGui::SameLine();
+        if (fn_ui::button("Cancel", fn_ui::ButtonVariant::Subtle)) {
+            app.show_new_project_modal = false;
+            app.new_project_error.clear();
+        }
+    }
+    fn_ui::modal_dialog_end();
+    return created;
+}
+
 bool views_open_modal(AppState& app) {
     if (!app.show_open_modal) return false;
     bool opened = false;