feat: add Settlement actor type with Overview/Buildings/Inventory tabs

- New TypeDataModel: archetype, territory, renown, currency (gp/sp/cp),
  garrison, underSiege, isCapital, founded, taxNotes, description, notes
- 3-tab ApplicationV2 sheet with drag & drop for building/weapon/armor/equipment
- Currency steppers (+/−), building constructed toggle, qty controls
- LESS-based CSS (settlement-sheet.less) + base.less updated for shared styles
- Full i18n keys in lang/en.json (8 settlement archetypes)
- system.json: registered settlement actor type

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

less/base.less

@@ -36,7 +36,8 @@
 
 // Shared actor content base
 .oathhammer .character-content,
-.oathhammer .npc-content {
+.oathhammer .npc-content,
+.oathhammer .settlement-content {
   font-family: @font-body;       // Calibri — standard text per design_rules.md
   font-size: @font-size-base;
   color: @color-dark;