feat: add rescan dead domains checkbox to validator

Adds rescan_dead flag that causes _filter_unvalidated to treat
previously-dead domains as needing a fresh check. Useful after
fixing the http/https detection bug.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/static/index.html

@@ -578,6 +578,10 @@ tr:hover td{background:rgba(255,255,255,.025)}
         <label>TLD filter <span style="font-weight:400;color:var(--muted)">(leave empty for all domains)</span></label>
         <input type="text" x-model="valTld" placeholder="es  or  com  or  ro" style="width:180px" :disabled="valSt.running">
       </div>
+      <label class="tog" style="padding-bottom:6px" :style="valSt.running?'opacity:.4':''">
+        <input type="checkbox" x-model="valRescan" :disabled="valSt.running">
+        <strong>Rescan dead</strong> <span>(recheck previously dead domains)</span>
+      </label>
       <button class="btn bs" :disabled="valSt.running" @click="startValidator()">▶ Start Validator</button>
       <button class="btn bd" :disabled="!valSt.running" @click="stopValidator()">⏹ Stop</button>
       <span x-show="valSt.running" style="font-size:11px;color:var(--accent2);padding-bottom:6px">⚡ Running…</span>
@@ -751,7 +755,7 @@ function app() {
     f: {tld:'',keyword:'',min_score:0,cms:'',live_only:false,alpha_only:false,no_sld:false,kit_digital_only:false,exclude_assessed:false,limit:'100',prescreen_status:'',niche:'',site_type:''},
     qst: {}, customDomains: '',
     valSt: {running:false,processed:0,live:0,dead:0,parked:0,redirect:0,skipped:0,offset:0,rate:0},
-    valTld: '',
+    valTld: '', valRescan: false,
     leadsQ: {quality:'', country:'', limit:'50'},
     leadsData: [], leadsTotal: 0, leadsPage: 1, leadsLoading: false,
     prescreening: false,
@@ -945,6 +949,7 @@ function app() {
     async startValidator() {
       const p = new URLSearchParams();
       if(this.valTld.trim()) p.set('tld', this.valTld.trim());
+      if(this.valRescan) p.set('rescan_dead', 'true');
       await fetch('/api/validator/start'+(p.toString()? '?'+p : ''), {method:'POST'});
       this.notify('Validator started', 'success');
       await this.loadValStatus();