refactor: apply 'one folder = one purpose' rule to overflowed packages

- Split by sub-purpose: storage/sql -> schema/+query/+repo/, adaptive/core ->
  calc/+metrics/+model/, command/admin -> ops/+support/, api/event ->
  session/+score/+generation/, menu/core -> screen/, config/core -> merge/,
  config/options -> section/, player/service -> ui/, hook/papi -> resolver/
  (done), mode/impl -> solo/+multi/+barrier/ (done)
- Move util/gui migration stubs -> menu/gui; lpschem POJOs -> pojo/
- Cross-package classes made public (signatures unchanged); fixed imports
- docs/ARCHITECTURE.md + TODO.md updated
- Build green: checkstyle 0 errors, PMD 34

src/main/java/dev/loki/loparkour/util/gui/PagedMenu.java

@@ -1,42 +0,0 @@
-package dev.loki.loparkour.util.gui;
-
-import dev.loki.loparkour.config.locale.Locales;
-import dev.loki.loparkour.util.item.Item;
-import org.bukkit.entity.Player;
-
-import java.util.List;
-
-/**
- * Legacy paged menu stub — real menus use LoLib GUI.
- */
-public class PagedMenu {
-    private final int rows;
-    private final String title;
-    private List<Item> items = List.of();
-
-    public PagedMenu(int rows, String title) {
-        this.rows = rows;
-        this.title = title;
-    }
-
-    public PagedMenu addToDisplay(List<Item> items) {
-        this.items = items;
-        return this;
-    }
-
-    public PagedMenu item(int slot, Item item) {
-        return this;
-    }
-
-    public PagedMenu nextPage(int slot, Item item) {
-        return this;
-    }
-
-    public PagedMenu prevPage(int slot, Item item) {
-        return this;
-    }
-
-    public void open(Player player) {
-        Locales.send(player, "other.paged_menu_unavailable", title, rows, items.size());
-    }
-}