feat(storm-intel): Phase 4+5 — Tomorrow.io forecast overlay and canvasser zone assignment

- Tomorrow.io 7-day forecast strip with weather icons, storm score bar, and per-day risk color coding
- High-risk alert banner in forecast strip when any day scores >=65
- api/storm-forecast.js: Vercel proxy that reads TOMORROW_API_KEY server-side; graceful empty response when key unset
- useStormForecast hook: USE_MOCK=false with realistic MOCK_FORECAST fallback
- ZoneDrawingLayer: click-to-place polygon vertices using react-leaflet useMapEvents; disables double-click zoom while active; shows live vertex dots + dashed preview polygon
- ZoneLayer: renders stormZones as colored semi-transparent polygons with agent initials at centroid
- ZoneAssignmentModal: name + canvasser picker + color selector + optional storm link; portaled modal
- StormIntelPage: Draw Zone button (Admin/Owner only); drawing state/cancel flow; stormZones displayed on map; zone summary strip in sidebar; StormDetailDrawer has working "Draw Canvasser Zone" action
- FieldStormZonePage: canvasser mobile view at /field/storm-zones showing assigned zones with map, linked storm details, conversion window badge, and peak window alert
- Layout: Storm Zones entry in FIELD_AGENT nav
- App: /field/storm-zones route (FIELD_AGENT + Admin + Owner)

src/components/Layout.jsx

@@ -191,6 +191,7 @@ const Layout = () => {
                     { to: "/emp/fa/maps", icon: Map, label: "My Map" },
                     { to: "/emp/fa/leads", icon: ClipboardList, label: "Leads" },
                     { to: "/emp/fa/kanban", icon: LayoutGrid, label: "Pipeline" },
+                    { to: "/field/storm-zones", icon: CloudLightning, label: "Storm Zones" },
                     {
                         to: "/emp/fa/pro-canvas",
                         icon: LayoutDashboard,