Two structural fixes from the Desktop performance audit (P2 tier):
1. Scope live tool-diff subscriptions. `ToolEntry` subscribed to the whole
`$toolDiffs` map via `useStore`, so one `recordToolDiff` re-rendered every
mounted tool row. Add a cached per-toolCallId derived atom
(`$toolInlineDiff(id)`, mirroring the existing `$toolDisclosureOpen` pattern);
computed() only notifies when that id's diff string changes, so a live patch
re-renders one row.
2. Narrow profile / gateway-switch query invalidation. Both the active-profile
subscription and `wipeSessionListsForGatewaySwitch` called keyless
`queryClient.invalidateQueries()`, refetching account/marketplace/onboarding
caches on every switch. Add `invalidateProfileScopedQueries()` with a
denylist of profile-independent roots (billing, marketplace-themes,
onboarding-model-options, contrib-logs-tail). A denylist is correctness-safe:
a root we forget just refetches (cheap), whereas an allowlist that misses a
profile-scoped key would paint the previous profile's data.
Tests: per-tool notify isolation, and real-QueryClient invalidation partition
(profile-scoped invalidated, global left intact, unknown keys invalidated).
