Sponsor section, live contributor count, fix Store-highlight scoping

1. Download: the Microsoft Store link's promoted styling is now scoped to
   .is-recommended, so it only glows when the visitor is actually on
   Windows — previously it read as highlighted on every platform
2. New Sponsor section (+nav/footer links): Open Collective CTA with
   impact tiles — AI development subscriptions, control-device lab,
   public ledger — plus a gear-donation path for the device lab
3. Contribute facts: live contributor count via the GitHub contributors
   Link-header trick (per_page=1&anon=1 -> rel=last page), 1h cache,
   static 46 fallback

Author: patj

assets/js/downloads.js

@@ -113,7 +113,38 @@
       .catch(function () { /* keep fallback /releases/latest links */ });
   }
 
-  function init() { highlight(); loadRelease(); }
+  // Live contributor count: GitHub exposes the total as the last-page number
+  // in the Link header of /contributors?per_page=1 (anon=1 counts everyone).
+  function loadContributors() {
+    var els = document.querySelectorAll('[data-contributor-count]');
+    if (!els.length || !window.fetch) return;
+    var CC_KEY = 'aetherContributorCount';
+    try {
+      var c = JSON.parse(localStorage.getItem(CC_KEY));
+      if (c && Date.now() - c.t < TTL) {
+        for (var i = 0; i < els.length; i++) els[i].textContent = c.n;
+        return;
+      }
+    } catch (e) {}
+    fetch('https://api.github.com/repos/' + REPO + '/contributors?per_page=1&anon=1', {
+      headers: { Accept: 'application/vnd.github+json' }
+    })
+      .then(function (res) {
+        if (!res.ok) throw new Error('github ' + res.status);
+        var link = res.headers.get('Link') || '';
+        var m = link.match(/[?&]page=(\d+)>;\s*rel="last"/);
+        if (!m) throw new Error('no last page');
+        return parseInt(m[1], 10);
+      })
+      .then(function (n) {
+        if (!n) return;
+        try { localStorage.setItem(CC_KEY, JSON.stringify({ t: Date.now(), n: n })); } catch (e) {}
+        for (var i = 0; i < els.length; i++) els[i].textContent = n;
+      })
+      .catch(function () { /* keep the static fallback count */ });
+  }
+
+  function init() { highlight(); loadRelease(); loadContributors(); }
   if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', init);
   else init();
 })();

index.html

@@ -45,6 +45,7 @@
         <a href="#built">How it's built</a>
         <a href="#partners">Partners</a>
         <a href="#contribute">Contribute</a>
+        <a href="#sponsor">Sponsor</a>
         <div class="nav-item">
           <button class="nav-dd-toggle" type="button" aria-haspopup="true">
             Support
@@ -471,6 +472,7 @@ <h2 style="margin-top:16px; font-size: clamp(28px, 4vw, 40px);">Help build the c
           <a class="btn btn-ghost" href="https://github.com/aethersdr/AetherSDR/discussions" target="_blank" rel="noopener">Join Discussions</a>
         </div>
         <div class="contribute-facts">
+          <span class="f"><b data-contributor-count>46</b> contributors and counting</span>
           <span class="f"><b>~50</b> PRs merged / week</span>
           <span class="f"><b>GPG-signed</b> commits</span>
           <span class="f"><b>≥6</b> AI tools in the codebase</span>
@@ -481,6 +483,47 @@ <h2 style="margin-top:16px; font-size: clamp(28px, 4vw, 40px);">Help build the c
     </div>
   </section>
 
+  <!-- ===================== SPONSOR ===================== -->
+  <section class="block" id="sponsor" style="padding-top: 10px;">
+    <div class="wrap">
+      <div class="cta-banner">
+        <span class="eyebrow"><span class="dot"></span> Sponsor AetherSDR</span>
+        <h2 style="margin-top:16px;">Fuel the next release</h2>
+        <p>AetherSDR is free, GPL, and always will be. Sponsorship through
+        <a href="https://opencollective.com/aethersdr" target="_blank" rel="noopener">Open Collective</a>
+        directly drives the product forward — it funds the AI development subscriptions behind
+        our ~50 merged PRs a week, and puts real control hardware on the test bench so knobs,
+        dials, and decks work the day we ship them.</p>
+        <div class="sponsor-impact">
+          <div class="imp">
+            <div class="k grad-text">AI development</div>
+            <div class="v">Claude Code &amp; AetherClaude subscriptions — the engine behind the release pace</div>
+          </div>
+          <div class="imp">
+            <div class="k grad-text">Device lab</div>
+            <div class="v">Buying the knobs, dials, and Stream Decks we implement and test on real hardware</div>
+          </div>
+          <div class="imp">
+            <div class="k grad-text">Public ledger</div>
+            <div class="v">Every dollar in and out is visible on Open Collective — no black box</div>
+          </div>
+        </div>
+        <div class="hero-cta" style="justify-content:center; margin-top:26px;">
+          <a class="btn btn-primary" href="https://opencollective.com/aethersdr" target="_blank" rel="noopener">
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M20.8 8.6a5.5 5.5 0 0 0-9.8-2.6 5.5 5.5 0 0 0-9.8 2.6c0 5.3 7.2 9.9 9.8 11.4 2.6-1.5 9.8-6.1 9.8-11.4z" transform="translate(1 1) scale(0.92)"/></svg>
+            Sponsor on Open Collective
+          </a>
+          <a class="btn btn-ghost" href="https://opencollective.com/aethersdr#category-BUDGET" target="_blank" rel="noopener">See the public ledger</a>
+        </div>
+        <p style="color:var(--muted); font-size:13.5px; margin-top:20px;">
+          Prefer to contribute gear instead? Controller hardware loans and donations for the
+          device lab are just as welcome —
+          <a href="https://github.com/aethersdr/AetherSDR/discussions">start a thread</a>.
+        </p>
+      </div>
+    </div>
+  </section>
+
   <!-- ===================== FOOTER ===================== -->
   <footer class="foot">
     <div class="wrap">
@@ -502,6 +545,7 @@ <h4>Community</h4>
           <a href="https://github.com/aethersdr/AetherSDR/discussions">Discussions</a>
           <a href="https://github.com/aethersdr/AetherSDR/issues">Issue tracker</a>
           <a href="https://github.com/aethersdr/AetherSDR/blob/main/CONTRIBUTING.md">Contributing</a>
+          <a href="https://opencollective.com/aethersdr">Sponsor us</a>
         </div>
         <div class="foot-col">
           <h4>Resources</h4>

styles.css

@@ -367,14 +367,16 @@ section.block { padding: 84px 0; }
 }
 .dl-card .variants a:hover { border-color: var(--cyan); color: var(--ink); background: rgba(93,227,255,0.06); }
 .dl-card .variants .arch { color: var(--muted); font-size: 12.5px; font-family: var(--mono); }
-.dl-card .variants a.primary-dl {
+/* The Store link is only visually promoted when this card is the visitor's
+   detected platform — otherwise it renders like any other variant. */
+.dl-card.is-recommended .variants a.primary-dl {
   border-color: var(--line-hi);
   background: var(--grad-soft);
   color: var(--ink);
   font-weight: 640;
 }
-.dl-card .variants a.primary-dl .arch { color: var(--cyan); }
-.dl-card .variants a.primary-dl:hover { border-color: var(--cyan); background: rgba(93,227,255,0.12); }
+.dl-card.is-recommended .variants a.primary-dl .arch { color: var(--cyan); }
+.dl-card.is-recommended .variants a.primary-dl:hover { border-color: var(--cyan); background: rgba(93,227,255,0.12); }
 .dl-card .winget {
   margin-top: 2px;
   font-family: var(--mono);
@@ -448,6 +450,25 @@ section.block { padding: 84px 0; }
 }
 .bridge-guard svg { width: 16px; height: 16px; stroke: var(--aqua); fill: none; stroke-width: 1.8; flex: none; margin-top: 2px; }
 
+/* ---------- Sponsor ---------- */
+.sponsor-impact {
+  display: grid;
+  grid-template-columns: repeat(3, 1fr);
+  gap: 14px;
+  max-width: 860px;
+  margin: 28px auto 0;
+  text-align: left;
+}
+.sponsor-impact .imp {
+  border: 1px solid var(--line);
+  border-radius: var(--radius-sm);
+  background: rgba(255,255,255,0.02);
+  padding: 16px 18px;
+}
+.sponsor-impact .k { font-size: 15px; font-weight: 720; letter-spacing: -0.01em; }
+.sponsor-impact .v { color: var(--muted); font-size: 13.5px; margin-top: 5px; line-height: 1.5; }
+@media (max-width: 700px) { .sponsor-impact { grid-template-columns: 1fr; } }
+
 /* ---------- Contribute ---------- */
 .contribute-actions { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; margin-top: 24px; }
 .contribute-facts {