## What
Lets a many-to-one relation be selected as the **leaf** of an advanced
(nested) filter. Previously the nested-field submenu excluded relations,
so you could filter `Opportunities WHERE company.Name contains X` but
not `Opportunities WHERE company.accountOwner = me`.
## How it works
Selecting a relation leaf filters by its **foreign key** —
`company.accountOwnerId = X` — a single hop the backend already resolves
on the joined table (`{ company: { accountOwnerId: { in: [...] } } }`).
It is **not** a multi-hop traversal: filtering on a *scalar field of*
the related record (e.g. `company.accountOwner.name`) stays excluded,
since that needs a second join the backend caps at one hop.
Two changes:
- **`AdvancedFilterRelationTargetFieldSelectMenu`** — stop excluding
many-to-one relations from the nested-field submenu.
- **`ObjectFilterDropdownRecordSelect`** — resolve the record picker's
object from the *leaf* relation's target (e.g. WorkspaceMember,
including the "Me" pin) rather than the source relation's object. The
source-field fallback applies only when there is no leaf.
## Testing
- Added `turnRecordFilterIntoRecordGqlOperationFilter` unit cases
asserting a relation leaf (and `= me`) compiles to the FK form — 59/59.
- typecheck + lint green (twenty-front, twenty-shared).
Seeding an onboarding view that uses this filter will follow in a
separate PR.
