fix: rename SettingsPermissionsGuard to SettingsPermissionGuard for consistency (#15712)

## Problem

The ESLint rule `graphql-resolvers-should-be-guarded` introduced in
#15392 was failing on main because the guard `SettingsPermissionsGuard`
had inconsistent naming.

## Root Cause

The guard was named `SettingsPermissionsGuard` (with an 's') which was
inconsistent with other permission guards:
- ✅ `CustomPermissionGuard`  
- ✅ `NoPermissionGuard`
- ✅ `ImpersonatePermissionGuard`
- ❌ `SettingsPermissionsGuard` (inconsistent!)

The ESLint rule checks if guard names end with `PermissionGuard`, but
`SettingsPermissionsGuard` ends with `sGuard`, so it wasn't recognized
as a permission guard.

## Solution

Renamed the guard to be consistent with the naming convention:

1. ✅ Renamed file: `settings-permissions.guard.ts` →
`settings-permission.guard.ts`
2. ✅ Renamed export: `SettingsPermissionsGuard` →
`SettingsPermissionGuard`
3. ✅ Renamed internal class: `SettingsPermissionsMixin` →
`SettingsPermissionMixin`
4. ✅ Updated all 122 references across 44 files in the codebase
5. ✅ Renamed test file: `settings-permissions.guard.spec.ts` →
`settings-permission.guard.spec.ts`

## Testing

- ✅ `npx nx run twenty-server:lint` passes
- ✅ `npx nx run twenty-server:typecheck` passes
- ✅ No references to the old name remain in the codebase
- ✅ All previously failing resolver files now pass ESLint validation

## Related

Fixes issues introduced in #15392

packages/twenty-server/src/engine/metadata-modules/object-metadata/object-metadata.module.ts

@@ -11,7 +11,7 @@ import { NestjsQueryTypeOrmModule } from '@ptc-org/nestjs-query-typeorm';
 import { TypeORMModule } from 'src/database/typeorm/typeorm.module';
 import { FeatureFlagEntity } from 'src/engine/core-modules/feature-flag/feature-flag.entity';
 import { FeatureFlagModule } from 'src/engine/core-modules/feature-flag/feature-flag.module';
-import { SettingsPermissionsGuard } from 'src/engine/guards/settings-permissions.guard';
+import { SettingsPermissionGuard } from 'src/engine/guards/settings-permission.guard';
 import { WorkspaceAuthGuard } from 'src/engine/guards/workspace-auth.guard';
 import { DataSourceModule } from 'src/engine/metadata-modules/data-source/data-source.module';
 import { FieldMetadataEntity } from 'src/engine/metadata-modules/field-metadata/field-metadata.entity';
@@ -98,7 +98,7 @@ import { WorkspaceMigrationV2Module } from 'src/engine/workspace-manager/workspa
           },
           create: {
             many: { disabled: true },
-            guards: [SettingsPermissionsGuard(PermissionFlagType.DATA_MODEL)],
+            guards: [SettingsPermissionGuard(PermissionFlagType.DATA_MODEL)],
           },
           update: { disabled: true },
           delete: { disabled: true },