Code quality improvements from code review

- Add admin-only authorization for company and projects CRUD operations
- Create requireAccountId middleware to eliminate code duplication
- Standardize error handling (use next(error) consistently)
- Change error messages to Slovak language

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

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

src/controllers/contact.controller.js

@@ -33,7 +33,7 @@ export const getContacts = async (req, res, next) => {
       data: contacts,
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -79,7 +79,7 @@ export const discoverContacts = async (req, res, next) => {
       data: potentialContacts,
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -138,7 +138,7 @@ export const addContact = async (req, res, next) => {
       message: 'Kontakt pridaný a emaily synchronizované',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -172,7 +172,7 @@ export const removeContact = async (req, res, next) => {
       message: result.message,
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -208,7 +208,7 @@ export const updateContact = async (req, res, next) => {
       message: 'Kontakt aktualizovaný',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -255,7 +255,7 @@ export const linkCompanyToContact = async (req, res, next) => {
       message: 'Firma bola linknutá ku kontaktu',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -290,7 +290,7 @@ export const unlinkCompanyFromContact = async (req, res, next) => {
       message: 'Firma bola odlinknutá od kontaktu',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -327,6 +327,6 @@ export const createCompanyFromContact = async (req, res, next) => {
       message: 'Firma bola vytvorená z kontaktu',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };