Forward hailAt/hailSize in the wind router (decision 13 plumbing)

A's router tripwire ('wind router forwards EVERYTHING the real wind exposes')
went red the moment weather.js grew hailAt/hailSize — which is the tripwire doing
exactly its job. A's own comment on createWindRouter is the standing instruction:
"Anything new on the wind contract must be added here too." Without this, the
garden score (which hangs entirely off gardenHailExposure → hailAt) would be
inert in the game while every assert passed — the precise silent-swallow this
tripwire exists to prevent, and the second time it would have bitten hail.

Two forwards, matching the existing pattern. Selftest 216/0/0, tripwire green,
and hail now reaches skyfx in-game with no console patch (verified). Flagged to A
in THREADS since it's their file.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/world/js/main.js

@@ -172,6 +172,7 @@ export function createWindRouter(all) {
     rainAt: (t) => active.rainAt(t),
     rainMmPerHour: (t) => active.rainMmPerHour(t),
     rainDepthMm: (a, b) => active.rainDepthMm(a, b),
+    hailAt: (t) => active.hailAt(t),                 // SPRINT5 decision 13 — the garden score hangs off this
     dirAt: (t) => active.dirAt(t),
 
     setShelters(list) {
@@ -188,6 +189,7 @@ export function createWindRouter(all) {
       })));
     },
 
+    get hailSize() { return active.hailSize; },      // SPRINT5 decision 13
     get duration() { return active.duration; },
     get gusts() { return active.gusts; },
     get def() { return active.def; },