proxmox: bring sub-tabs onto the showFilterToolbar contract

ProxmoxPageSurface pre-dated the v5-style operator-controls bridge
(65b069dbb) and the source-filter suppression helper (294ac1da0), so
its embedded WorkloadsSurface / StorageSurface mounts were still
running in `tableOnly` mode with no canonical filter toolbar — no
search, no status chips, no view-mode toggle, no grouping control.
The /docker/containers, /kubernetes/pods, /truenas/storage, etc. all
already had this; only Proxmox was missing it.

Add `showFilterToolbar` (and `suppressPlatformFilter` on the
Workloads embed) to:
- /proxmox/overview (Workloads — grouped)
- /proxmox/storage (StorageSurface — Source chip auto-suppressed by
  the existing `forcedSourceFilter` rule from 294ac1da0)
- /proxmox/ceph (StorageSurface forced to pools view)

Recovery embeds on /proxmox/replication and /proxmox/backups are
left as-is — RecoverySurface does not yet support
`showFilterToolbar`; that's the next thread.

Browser verification (Playwright, chromium, live mock-mode):
- 9 tests pass. Every-sub-tab operator-controls audit still green.

Contract-neutral bypass: PULSE_ALLOW_CONTRACT_NEUTRAL_COMMIT set.
No public-contract shape changes, no new files — just bringing
ProxmoxPageSurface onto the same opt-in props every other platform
page already uses.

frontend-modern/src/features/proxmox/ProxmoxPageSurface.tsx

@@ -151,12 +151,19 @@ export function ProxmoxPageSurface() {
                 useWorkloads
                 embedded
                 tableOnly
+                showFilterToolbar
+                suppressPlatformFilter
                 forcedPlatform={PROXMOX_PLATFORM_FILTER}
                 forcedGroupingMode="grouped"
               />
             </Show>
             <Show when={activeTab() === 'storage'}>
-              <StorageSurface embedded tableOnly forcedSourceFilter={PROXMOX_PLATFORM_FILTER} />
+              <StorageSurface
+                embedded
+                tableOnly
+                showFilterToolbar
+                forcedSourceFilter={PROXMOX_PLATFORM_FILTER}
+              />
             </Show>
             <Show when={activeTab() === 'replication'}>
               <RecoverySurface embedded tableOnly forcedPlatformFilter={PROXMOX_PLATFORM_FILTER} />
@@ -168,6 +175,7 @@ export function ProxmoxPageSurface() {
               <StorageSurface
                 embedded
                 tableOnly
+                showFilterToolbar
                 forcedView="pools"
                 forcedSourceFilter={PROXMOX_PLATFORM_FILTER}
               />