chore(18-01): remove quote builder route, exclusive components, and SendQuoteModal entry point (CLEAN-02)

- Delete src/app/admin/quotes/new/page.tsx and actions.ts re-export
- Delete QuoteBuilderForm, OfferSelector, PriceOverrideInput, QuotePreview components
- Rewrite SendQuoteModal: remove "Crea Nuovo" tab and window.location navigation to quotes/new
- Remove stale JSDoc comment referencing /admin/quotes/new from admin-queries.ts

src/lib/admin-queries.ts

@@ -859,7 +859,6 @@ export async function getQuotesByClient(clientId: string): Promise<Quote[]> {
 
 /**
  * Get all offer macros with their micros (ordered by sort_order)
- * Used by: /admin/quotes/new form (OfferSelector dropdown)
  */
 export async function getAllOfferMacrosWithMicros(): Promise<
   (OfferMacro & { micros: OfferMicro[] })[]