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/auth.controller.js

@@ -57,7 +57,7 @@ export const login = async (req, res, next) => {
     // Log failed login
     await logLoginAttempt(username, false, ipAddress, userAgent, error.message);
 
-    return next(error);
+    next(error);
   }
 };
 
@@ -84,7 +84,7 @@ export const setPassword = async (req, res, next) => {
       message: 'Heslo úspešne nastavené',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -114,7 +114,7 @@ export const linkEmail = async (req, res, next) => {
       message: 'Email účet úspešne pripojený a overený',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -135,7 +135,7 @@ export const skipEmail = async (req, res, next) => {
       message: 'Email setup preskočený',
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -164,7 +164,7 @@ export const logout = async (req, res, next) => {
       message: result.message,
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -183,7 +183,7 @@ export const getSession = async (req, res, next) => {
       },
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };
 
@@ -201,6 +201,6 @@ export const getMe = async (req, res, next) => {
       },
     });
   } catch (error) {
-    return next(error);
+    next(error);
   }
 };