v1.6.9: cleanup offer dead columns, add item template picker to offer form

- Remove dead DB columns: uuid, sync_version from quotations/quotation_items/scope_sections; is_deleted from quotation_items/scope_sections; content_editor_height from scope_sections
- Remove unused scope_title/scope_description from offer form state
- Remove dead CSS: offers-template-menu, offers-draft-indicator, exchange-rate
- Remove dead scope_title translation key from offers PDF
- Fix duplicate Customer interface in OfferDetail.tsx (use shared type)
- Add missing title field to ScopeTemplate interface
- Add item template picker dropdown next to "Přidat položku" button

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/admin/lib/queries/offers.ts

@@ -19,6 +19,7 @@ export interface ScopeSection {
 export interface ScopeTemplate {
   id: number;
   name: string;
+  title?: string;
   description?: string;
   scope_template_sections?: ScopeSection[];
 }
@@ -134,8 +135,6 @@ export interface OfferDetailData {
   language: string;
   vat_rate: number;
   apply_vat: boolean;
-  scope_title: string;
-  scope_description: string;
   items?: OfferItemData[];
   sections?: OfferSectionData[];
   status: string;