feat: Add company linking to personal contacts

- Add companyId column to personal_contacts table
- Update personal-contact service to include companyName in list
- Add getContactsByCompanyId function for company contacts endpoint
- Add GET /companies/:companyId/contacts endpoint
- Add companyId to contact validation schema

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/routes/personal-contact.routes.js

@@ -12,6 +12,7 @@ const createContactSchema = z.object({
   phone: z.string().min(3, 'Telefón je povinný'),
   email: z.string().email('Neplatný email'),
   secondaryEmail: z.union([z.string().email('Neplatný email'), z.literal('')]).optional(),
+  companyId: z.union([z.string().uuid(), z.literal(''), z.null()]).optional(),
 })
 
 const updateContactSchema = createContactSchema.partial()