Fixed world clock: no player time controls (ISS-117)

The world always runs at WORLD_TIME_SCALE = 24 (lib/worldClock.ts). A server
background tick (instrumentation.ts -> startBackgroundTick, 1 s interval)
advances the sim with no open browser; idle-pause freezes the clock exactly
while no plane is flying or in repair. Fresh worlds start year 2000
(STARTING_CLOCK_MS in seed.ts).

- Removed: POST /api/sim + OpenAPI entry, applyTimeControls/clampTimeScale,
  lib/timeScale.ts, LeftPane pause button + scale slider machinery,
  ISS-057 slow-on-landing/resume in flyPlane.
- Snapshot simState is now { clockMs } only; client extrapolates at the fixed
  rate between polls and freezes while idle (useSimClock).
- New test-only hook POST /api/test/set-timescale behind FLIGHT_TEST_HOOKS=1
  (sibling of set-health); all e2e setScale helpers call it, afterEach restores
  the world rate. E2E pause tests replaced by idle-pause assertions; sim.spec.ts
  activates the world via set-health + /repair for advance/expiry tests.

app/page.tsx

@@ -16,7 +16,7 @@ export default function Home() {
   // Single polling source for the whole shell (v0.9.0): one /api/state loop, snapshot passed
   // down as props so later panes can share it without extra poll loops. applySnapshot (v0.10.0)
   // lets a pane push an action endpoint's full response snapshot in immediately.
-  const { state, loading, error, refresh, applySnapshot } = useGameState(1000);
+  const { state, loading, error, applySnapshot } = useGameState(1000);
 
   // ISS-002 (v0.15.0): the side panels' hover target — shared here so hovering a row in
   // either pane highlights the matching plane/route/airports on the map.
@@ -45,7 +45,7 @@ export default function Home() {
     <div className="app-shell">
       {/* ISS-021 (v0.20.0) — applySnapshot also reaches the left pane: its On board section's
           fly/abandon actions push their response snapshot into the shared state */}
-      <LeftPane state={state} loading={loading} error={error} onRefresh={refresh} applySnapshot={applySnapshot} onHover={setHovered} onError={onError} />
+      <LeftPane state={state} loading={loading} error={error} applySnapshot={applySnapshot} onHover={setHovered} onError={onError} />
       {/* v0.11.0 — the same polled snapshot drives the map's plane markers + route lines;
           ISS-010 (v0.18.0) — applySnapshot lets the airport popup's Relocate row push its
           action response into the shared state, exactly like RightPane does */}