## Context
Since #19890 (Translate standard page layouts), the server's
`PageLayoutTab.title` resolver translates standard tab titles at query
time. A workspace member in French viewing a `messageChannel` (or any
system object with a standard page layout) receives `tab.title =
"Accueil"` / `"Chronologie"` instead of `"Home"` / `"Timeline"`.
The `SYSTEM_OBJECT_TABS` guard in `PageLayoutTabsRenderer` was comparing
against an English-only literal allow-list, so every tab was dropped,
`sortedTabs` became empty, and `<PageLayoutMainContent />` never mounted
— the record page rendered blank (no fields, timeline, email thread,
etc.).
## Fix
Only run the allow-list filter when the resolved layout is the synthetic
`DEFAULT_RECORD_PAGE_LAYOUT` (the client-side fallback for the few
system objects with no server-side standard page layout config, e.g.
`workspaceMember`, `attachment`, `message`). That layout ships hardcoded
English tabs, so the English allow-list still works in every locale.
System objects that do have a server-side standard page layout
(`messageChannel`, `connectedAccount`, `workflowRun`, …) are no longer
filtered at all, the server only ever persists Home/Timeline/Flow tabs
for them, so no filter is needed.
## Before
<img width="1262" height="722" alt="Screenshot 2026-05-04 at 15 15 54"
src="https://github.com/user-attachments/assets/348c9e9d-0ae1-4046-8ead-470ed8263cb5"
/>
## After
<img width="1281" height="658" alt="Screenshot 2026-05-04 at 15 15 36"
src="https://github.com/user-attachments/assets/7a9953b1-7320-4f1a-8c02-1688d3eda3ae"
/>
## Note
Next step should be to backfill those system objects with real record
page layouts so we can remove this filter logic
