Studio (AMD iGPU): split an iGPU row's total into VRAM and shared memory - #13421

Fixes #8942

What is wrong

On a Windows PC with an AMD graphics card and an AMD CPU with built-in graphics, Settings > System already splits the VRAM tile correctly since #9247:

VRAM   Unknown / 17.9 GiB VRAM + 34.2 GiB shared

The iGPU's own row under GPU devices still reads its whole 36.2 GiB as VRAM. The pill beside it says VRAM (Unknown VRAM in the screenshot, 4% VRAM once #11871 fills in the used figure), and nothing on the row says that 34.2 GiB of that is system RAM. The reporter's screenshot on #8942 (RX 9070 XT + Radeon(TM) Graphics) shows exactly that. The Unknown used figure on the same row was fixed separately by #11871.

The fix

The row now uses the same split the tile uses (gpuMemoryTotalsGb, applied to that one device):

The total on the right stays 36.2 GiB, since that is what the iGPU can actually allocate; the row now says what it is made of. Rows for discrete cards and Vulkan iGPUs (which #11305 already shows as estimated availability) render as before. Display only: nothing about model fit, budgets or the backend changes, and the strings reused are the tile's own (vramWithShared, sharedWithSystemRam), already translated in every locale.

Tests

tests/resources-device-row-shared-split.test.ts, built from the #8942 readings (15.9 GiB card, iGPU 36.2 GiB total with 34.2 GiB host-backed):

• the iGPU row splits into 2 GiB VRAM + 34.2 GiB shared
• the discrete card gets no split
• card + iGPU rows add up to the tile's dedicated / shared split
• a Linux ROCm APU (unified_memory without shared_memory) reads as shared, as the tile does
• zero or missing totals give no split
• the row in resources-tab.tsx drops VRAM from the pill and renders the split on its own line (beside the pill it truncated GPU 1, ROCM at the dialog's width)

Full frontend suite: 11761 / 11762 pass; the one failure (account-permissions.test.ts, sandbox popup) is a load flake that passes alone on both main and this branch. npm run typecheck and npm run i18n:check:strict clean; eslint on the touched files reports only the two errors already on main.

What it looks like

Two isolated Studio installs, one built from the merge base 3075b73d1 and one from head 2d10282d9, driven by the same Playwright scene. This box has no AMD iGPU, so both installs were served the gpu block from #8942 (RX 9070 XT 15.9 GiB, Radeon(TM) Graphics 36.2 GiB with 34.2 GiB host-backed, used figures filled in as #11871 now does) by replacing only that block of /api/system; everything else is each install's own live reading.