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/offers.css

@@ -46,33 +46,6 @@
   min-height: 32px;
 }
 
-/* Template dropdown menu */
-.offers-template-menu {
-  position: absolute;
-  top: 100%;
-  right: 0;
-  z-index: 100;
-  min-width: 200px;
-  max-height: 250px;
-  overflow-y: auto;
-  background: var(--bg-primary);
-  border: 1px solid var(--border-color);
-  border-radius: 0.5rem;
-  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
-  margin-top: 0.25rem;
-}
-
-.offers-template-menu-item {
-  padding: 0.5rem 0.75rem;
-  cursor: pointer;
-  font-size: 0.875rem;
-  transition: background var(--transition);
-}
-
-.offers-template-menu-item:hover {
-  background: var(--bg-secondary);
-}
-
 /* Language badges */
 .offers-lang-badge {
   display: inline-flex;
@@ -617,17 +590,6 @@
 }
 
 /* Offer draft indicator */
-.offers-draft-indicator {
-  display: flex;
-  align-items: center;
-  gap: 0.3rem;
-  font-size: 0.72rem;
-  font-weight: 500;
-  color: var(--text-tertiary);
-  margin-top: 0.2rem;
-  opacity: 0.8;
-}
-
 /* Filters */
 .admin-filters {
   display: flex;