[aq1018]

Two commits, one per cause of the linearized.spec.ts:17 flake ("ID 1 click not registered").

• Compile every route once before the browser specs. On a cold dev server, a route's first navigation waits for its modules to compile. Under load, that outlasted the 5 s expect after the ID 1 click: the click landed and the route was still loading. A global setup now loads every route once before the workers start. Pre-registered A/B, server held at 5% CPU, linearized test 1 on a fresh server: 17/30 failures before, 0/30 after (Fisher p = 3e-7). Every failure trace showed the selection landed and /servo modules still in flight.
• Keep the e2e server's watcher off. A rebuild of the shared wasm package mid-run hot-swapped session.tsx, which cannot Fast Refresh, so the session remounted and the selection was lost. That fits the original failure, which came mid-suite on an already-warm route. With the watcher on, three identical-byte rewrites of the package each caused a remount and 1 in-flight failure. With it off: 0 events, 72/72 passed.

Merge with rebase to keep the two commits.