fix: bust persisted query cache on deploy

[alanpeixinho]

What it is

Fixes /tree crashing with Cannot read properties of undefined (reading 'map') when a persisted React Query cache holds an origins payload without checkout_origins / test_origins (#2048).

• OriginSelect treats missing origin lists as [] so .map cannot throw.
• Persist cache is versioned with VITE_CACHE_BUSTER (dashboard version, or build-<timestamp> if empty) so a new deploy drops stale blobs.

How to test

Dev persist uses sessionStorage (prod: localStorage). Recover with sessionStorage.clear() then reload.

1. Open /tree and confirm the origin dropdown works.
2. Seed a mismatched origins shape and reload:

sessionStorage.setItem('REACT_QUERY_OFFLINE_CACHE', JSON.stringify({
buster: '', timestamp: Date.now(),
clientState: { mutations: [], queries: [{
  queryKey: ['origins'], queryHash: '["origins"]',
  state: { data: ['maestro'], dataUpdatedAt: Date.now(), status: 'success', fetchStatus: 'idle' },
}]},
}));
location.reload();

Expect: no “Something went wrong!”; origins refetch; dropdown populated.
3. Confirm stored buster matches the side-menu version (or build-… if no version).
4. Reload without editing the cache: same buster → hydrates, no crash.

Closes #2048