feat: move departments from projects to companies

Departments now belong to a Company, not a Project.
- New migration: recreates settings_departments with company_id (migrates existing data)
- Department model: company_id FK, company() relation
- Company model: departments() hasMany relation
- ProjectSetting model: removes departments() relation
- Controller: dept methods now take Company instead of ProjectSetting
- Routes: department CRUD moves to companies/{company}/departments
- View: departments section appears on each company card (purple theme);
  project body is now locations-only (single column)

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

app/Models/Settings/ProjectSetting.php

@@ -27,8 +27,4 @@ class ProjectSetting extends Model
         return $this->hasMany(\App\Models\Settings\Location::class, 'project_id');
     }
 
-    public function departments(): \Illuminate\Database\Eloquent\Relations\HasMany
-    {
-        return $this->hasMany(\App\Models\Settings\Department::class, 'project_id');
-    }
 }