fix: prod-bundle boot, cloud-existence leak, observation gating (final review)

- Wrap main.js body in async main() to eliminate top-level await deadlock in Rollup
- Add npc.lastPlan so clouds persist after hidden arrival/destruction until analytic envelope expires
- Add maxEnvelopeArrival() helper; rewrite playerClouds() to use lastPlan for envelope-gated clouds
- Block markSeen() while player is mid-lane (no observation from hyperspace)
- Pass obsSys=null to playerClouds when player is in a lane (don't exclude visible band from hyperspace)
- Galaxy map clicks now select-only (intel); jumps via Nav buttons / gate diamonds only
- Add preview script, favicon no-op, .playwright-mcp/ and *.png to .gitignore, update README controls text

src/sim/npc.js

@@ -102,6 +102,7 @@ export function planNpc(world, npc) {
     routeLanes: best.route.lanes, startSys: origin.systemId,
     startTime: t, ...itin,
   };
+  npc.lastPlan = null; // superseded; v1 simplification: a fresh cloud implies the previous run ended
   npc.state = 'transit';
   world.queue.push(itin.arriveTime, 'npc-arrive', { npcId: npc.id, planId });
 }
@@ -113,6 +114,7 @@ export function onNpcArrive(world, { npcId, planId }) {
   const plan = npc.plan;
   if (plan.finalOutcome === 'destroyed') {
     npc.alive = false;
+    npc.lastPlan = plan; // cloud persists from the envelope until observed/expired
     npc.plan = null;
     npc.cargo = null;
     npc.state = 'destroyed';
@@ -128,6 +130,7 @@ export function onNpcArrive(world, { npcId, planId }) {
     npc.credits = Math.round((npc.credits + price * npc.cargo.qty) * 100) / 100;
     world.stats.trades++;
   }
+  npc.lastPlan = plan; // unobserved arrival: the player's cloud persists a while
   npc.cargo = null;
   npc.plan = null;
   world.queue.push(world.t + DOCK_DELAY, 'npc-replan', { npcId });