Improve UX: better error messages, validation, and mobile fixes

FCC Compliance Check:
- FRN validation: shows "must be 10 digits" with digit count
- Auto-strips non-digits and pads to 10
- 30-second timeout with friendly message
- "Not found in any FCC database" with link to CORES
- Network error guidance
- FRN display uses overflow-wrap for mobile
- Error box uses innerHTML for clickable links

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

site/src/pages/tools/fcc-compliance-check.astro

@@ -100,7 +100,7 @@ import Base from "../../layouts/Base.astro";
         <p id="entity-dba" class="text-sm text-gray-500 hidden"></p>
         <p id="entity-address" class="text-sm text-gray-500 mt-1"></p>
         <p class="mt-2 text-sm text-gray-600">
-          FRN: <span id="entity-frn" class="font-mono font-semibold text-gray-800"></span>
+          FRN: <span id="entity-frn" class="font-mono font-semibold text-gray-800" style="overflow-wrap:break-word;"></span>
         </p>
         <div id="entity-details" class="hidden mt-3 space-y-1 text-sm text-gray-600">
           <p id="detail-filer-id"></p>
@@ -338,8 +338,17 @@ import Base from "../../layouts/Base.astro";
     frnInput.addEventListener("keydown", (e) => { if (e.key === "Enter") runCheck(); });
 
     async function runCheck() {
-      const frn = frnInput.value.trim();
+      const raw = frnInput.value.trim().replace(/\D/g, "");
-      if (!frn) return;
+      if (!raw) {
+        showError("Please enter a 10-digit FRN.");
+        return;
+      }
+      if (raw.length !== 10) {
+        showError("FRN must be exactly 10 digits (e.g., 0012345678). You entered " + raw.length + " digits.");
+        return;
+      }
+      const frn = raw.padStart(10, "0");
+      frnInput.value = frn;
 
       // Update URL
       const url = new URL(window.location);
@@ -352,22 +361,38 @@ import Base from "../../layouts/Base.astro";
       loadingEl.classList.remove("hidden");
 
       try {
-        const res = await fetch(`${API}/api/v1/fcc/lookup?frn=${frn}`);
+        const controller = new AbortController();
+        const timeout = setTimeout(() => controller.abort(), 30000);
+
+        const res = await fetch(`${API}/api/v1/fcc/lookup?frn=${frn}`, { signal: controller.signal });
+        clearTimeout(timeout);
+
         if (!res.ok) {
           const body = await res.json().catch(() => ({}));
-          throw new Error(body.detail || body.error || `Lookup failed (${res.status})`);
+          if (res.status === 400) {
+            throw new Error(body.error || "Invalid FRN format. Please check and try again.");
+          }
+          throw new Error(body.error || "FCC lookup failed. Please try again.");
         }
         const data = await res.json();
+        if (!data.entity_name && !data.cores?.entity_name && !data.filer_499) {
+          showError('FRN ' + frn + ' was not found in any FCC database. Verify your number at <a href="https://apps.fcc.gov/coresWeb/publicHome.do" target="_blank" style="color:#1e40af;text-decoration:underline;">FCC CORES</a>.');
+          return;
+        }
         renderResults(data);
       } catch (err) {
-        showError(err.message);
+        if (err.name === "AbortError") {
+          showError("The FCC databases are taking too long to respond. Please try again in a few moments.");
+        } else {
+          showError(err.message || "Could not reach the FCC databases. Please check your internet connection and try again.");
+        }
       } finally {
         loadingEl.classList.add("hidden");
       }
     }
 
     function showError(msg) {
-      errorMessage.textContent = msg;
+      errorMessage.innerHTML = msg;
       errorBox.classList.remove("hidden");
     }