feat: fix junction toggle persistence and add type-safe documentation paths (#17421)

## Summary

- **Fix junction relation toggle not being saved**: The form schema
wasn't tracking the `settings` field, so changes to
`junctionTargetFieldId` weren't marked as dirty
- **Add type-safe documentation paths**: Generate TypeScript constants
from `base-structure.json` to prevent broken documentation links
- **Create many-to-many relations documentation**: Step-by-step guide
for building many-to-many relations using junction objects
- **Update `getDocumentationUrl`**: Now uses shared constants from
`twenty-shared` for base URL, default path, and supported languages

## Key Changes

### Junction Toggle Fix
- Added `settings` field to the form schema in
`SettingsDataModelFieldRelationForm.tsx`
- Fixed the toggle to properly merge settings when updating
`junctionTargetFieldId`

### Type-Safe Documentation Paths
- New constants in `twenty-shared/constants`:
- `DOCUMENTATION_PATHS` - All 161 documentation paths as typed constants
  - `DOCUMENTATION_SUPPORTED_LANGUAGES` - 14 supported languages
  - `DOCUMENTATION_BASE_URL` / `DOCUMENTATION_DEFAULT_PATH`
- Generator script: `yarn docs:generate-paths`
- CI integration: Added to `docs-i18n-pull.yaml` workflow

### Documentation
- New article:
`/user-guide/data-model/how-tos/create-many-to-many-relations`
- Updated `/user-guide/data-model/capabilities/relation-fields.mdx` with
Lab warning and link

## Test plan
- [ ] Verify junction toggle saves correctly when enabled/disabled
- [ ] Verify documentation link opens correct localized page
- [ ] Verify `yarn docs:generate-paths` regenerates paths correctly

packages/twenty-front/src/modules/settings/data-model/fields/forms/morph-relation/components/SettingsDataModelFieldRelationForm.tsx

@@ -55,6 +55,12 @@ export const settingsDataModelFieldMorphRelationFormSchema = z.object({
   ),
   targetFieldLabel: z.string().min(1),
   iconOnDestination: z.string().min(1),
+  settings: z
+    .object({
+      junctionTargetFieldId: z.string().optional(),
+    })
+    .catchall(z.unknown())
+    .optional(),
 });
 
 export type SettingsDataModelFieldMorphRelationFormValues = z.infer<

packages/twenty-front/src/modules/settings/data-model/fields/forms/morph-relation/components/SettingsDataModelFieldRelationJunctionForm.tsx

@@ -1,16 +1,19 @@
+import { Trans, useLingui } from '@lingui/react/macro';
 import { useFormContext } from 'react-hook-form';
+import { useRecoilValue } from 'recoil';
+import { DOCUMENTATION_PATHS } from 'twenty-shared/constants';
+import { FieldMetadataType } from 'twenty-shared/types';
+import { isDefined } from 'twenty-shared/utils';
+import { IconLink } from 'twenty-ui/display';
 
+import { currentWorkspaceMemberState } from '@/auth/states/currentWorkspaceMemberState';
 import { useObjectMetadataItem } from '@/object-metadata/hooks/useObjectMetadataItem';
 import { useObjectMetadataItems } from '@/object-metadata/hooks/useObjectMetadataItems';
 import { SettingsOptionCardContentSelect } from '@/settings/components/SettingsOptions/SettingsOptionCardContentSelect';
 import { SettingsOptionCardContentToggle } from '@/settings/components/SettingsOptions/SettingsOptionCardContentToggle';
+import { getDocumentationUrl } from '@/support/utils/getDocumentationUrl';
 import { Select } from '@/ui/input/components/Select';
 import { isAdvancedModeEnabledState } from '@/ui/navigation/navigation-drawer/states/isAdvancedModeEnabledState';
-import { useLingui } from '@lingui/react/macro';
-import { useRecoilValue } from 'recoil';
-import { FieldMetadataType } from 'twenty-shared/types';
-import { isDefined } from 'twenty-shared/utils';
-import { IconLink } from 'twenty-ui/display';
 import { RelationType } from '~/generated-metadata/graphql';
 import { type SettingsDataModelFieldEditFormValues } from '~/pages/settings/data-model/SettingsObjectFieldEdit';
 
@@ -26,6 +29,12 @@ export const SettingsDataModelFieldRelationJunctionForm = ({
     useFormContext<SettingsDataModelFieldEditFormValues>();
 
   const isAdvancedModeEnabled = useRecoilValue(isAdvancedModeEnabledState);
+  const currentWorkspaceMember = useRecoilValue(currentWorkspaceMemberState);
+
+  const documentationUrl = getDocumentationUrl({
+    locale: currentWorkspaceMember?.locale,
+    path: DOCUMENTATION_PATHS.USER_GUIDE_DATA_MODEL_HOW_TOS_CREATE_MANY_TO_MANY_RELATIONS,
+  });
 
   const { objectMetadataItem: sourceObjectMetadataItem } =
     useObjectMetadataItem({ objectNameSingular });
@@ -34,7 +43,8 @@ export const SettingsDataModelFieldRelationJunctionForm = ({
 
   const relationType = watch('relationType') ?? RelationType.ONE_TO_MANY;
   const targetObjectIds = watch('morphRelationObjectMetadataIds') ?? [];
-  const junctionTargetFieldId = watch('settings.junctionTargetFieldId');
+  const currentSettings = watch('settings');
+  const junctionTargetFieldId = currentSettings?.junctionTargetFieldId;
 
   // Only applies to ONE_TO_MANY with single target
   if (
@@ -112,23 +122,40 @@ export const SettingsDataModelFieldRelationJunctionForm = ({
   const handleJunctionToggle = (checked: boolean) => {
     if (checked && junctionFieldOptions.length > 0) {
       setValue(
-        'settings.junctionTargetFieldId',
-        junctionFieldOptions[0].value,
+        'settings',
+        {
+          ...currentSettings,
+          junctionTargetFieldId: junctionFieldOptions[0].value,
+        },
         {
           shouldDirty: true,
         },
       );
     } else {
-      setValue('settings.junctionTargetFieldId', undefined, {
-        shouldDirty: true,
-      });
+      setValue(
+        'settings',
+        {
+          ...currentSettings,
+          junctionTargetFieldId: undefined,
+        },
+        {
+          shouldDirty: true,
+        },
+      );
     }
   };
 
   const handleSelectionChange = (selectedValue: string) => {
-    setValue('settings.junctionTargetFieldId', selectedValue, {
-      shouldDirty: true,
-    });
+    setValue(
+      'settings',
+      {
+        ...currentSettings,
+        junctionTargetFieldId: selectedValue,
+      },
+      {
+        shouldDirty: true,
+      },
+    );
   };
 
   return (
@@ -136,7 +163,19 @@ export const SettingsDataModelFieldRelationJunctionForm = ({
       <SettingsOptionCardContentToggle
         Icon={IconLink}
         title={t`This is a relation to a Junction Object`}
-        description={t`Will show linked records directly instead of intermediate junction record`}
+        description={
+          <Trans>
+            Build many-to-many relations.{' '}
+            <a
+              href={documentationUrl}
+              target="_blank"
+              rel="noopener noreferrer"
+              style={{ textDecoration: 'underline', color: 'inherit' }}
+            >
+              Learn more
+            </a>
+          </Trans>
+        }
         checked={isJunctionConfigEnabled}
         onChange={handleJunctionToggle}
         divider={isJunctionConfigEnabled}