Read project deployments from the virtual scope chain instead of endpoints.project

Replace the ownership predicate in `ProjectDeploymentOperationScope` (`src/ai/backend/manager/models/endpoint/scopes.py:20`) so the rows it bounds are read from the virtual scope chain instead of the legacy ownership column.

## Current

`EndpointRow.project == :project_id`

## Target

Resolve membership through `entity_memberships` joined to `virtual_scopes`, keyed on the parent scope's virtual scope node.

Helpers live in `src/ai/backend/manager/models/virtual_scope/queries.py`.

## Write side

Present. src/ai/backend/manager/models/endpoint/creators.py:79 declares member_of() -> (project_id, session_owner_id).

## Entry points

- `services/deployment/processors.py:343` -> `SearchDeploymentsInProjectAction`

## Note

No API handler reaches this action yet; it is wired only as far as the processor. Converting it now keeps a legacy read from landing when the handler is added.

## Done when

- The scope's `to_condition()` no longer references the legacy ownership column.
- A test proves the converted read returns the same rows as the column-based query on backfilled data.

JIRA Issue: BA-7529

Start in src/ai/backend/manager/models/endpoint/scopes.py:20 and inspect the virtual-scope query helpers in src/ai/backend/manager/models/virtual_scope/queries.py. Trace the read from services/deployment/processors.py:343 and compare it with member_of() in endpoint/creators.py:79. Done means to_condition() no longer uses the legacy ownership column and a test confirms identical rows on backfilled data.

Written by the indexing model from the issue text.