Add EDDM size, income, businesses and USPS map link (#13)

## Summary
Closes #13.
- Mirror Monica: join USPS EDDM GIS stats onto the carrier-route picker and link to the official EDDM map.
- GIS miss stays a dash and does not block Find routes; PCM households/cost unchanged.

site/client_site/static/js/postcard-routes.js

@@ -6,6 +6,27 @@
     return "$" + v.toFixed(2);
   }
 
+  function hhSize(n) {
+    if (n === null || n === undefined || n === "") return "—";
+    var v = Number(n);
+    if (Number.isNaN(v)) return "—";
+    return v.toFixed(1);
+  }
+
+  function income(n) {
+    if (n === null || n === undefined || n === "") return "—";
+    var v = Number(n);
+    if (Number.isNaN(v)) return "—";
+    return "$" + Math.round(v).toLocaleString("en-US");
+  }
+
+  function count(n) {
+    if (n === null || n === undefined || n === "") return "—";
+    var v = Number(n);
+    if (Number.isNaN(v)) return "—";
+    return String(v);
+  }
+
   function initPostcardRoutes(opts) {
     var form = document.getElementById("campaign-compose");
     if (!form) return;
@@ -18,6 +39,7 @@
     var tableWrap = document.getElementById("route-table-wrap");
     var tbody = document.getElementById("route-table-body");
     var selectedBox = document.getElementById("route-selected-cost");
+    var eddmLink = document.getElementById("eddm-map-link");
     var quoteUrl = opts.quoteUrl;
     var csrfToken = opts.csrfToken;
     var maxRoutes = 2;
@@ -173,6 +195,9 @@
           String(row.code) + "</label></td>" +
           "<td>" + String(row.text || "") + "</td>" +
           "<td>" + String(row.total) + "</td>" +
+          "<td>" + hhSize(row.household_size) + "</td>" +
+          "<td>" + income(row.median_income) + "</td>" +
+          "<td>" + count(row.businesses) + "</td>" +
           "<td>" + money(row.cost) + "</td></tr>";
       }).join("");
       tbody.querySelectorAll('input[name="route_code"]').forEach(function (box) {
@@ -207,6 +232,9 @@
         radius: radius
       }).then(function (data) {
         renderRoutes(data.routes || []);
+        if (eddmLink && data.eddm_map_url) {
+          eddmLink.href = data.eddm_map_url;
+        }
         if (!(data.routes || []).length) {
           setStatus("No carrier routes for that search.", true);
         } else {