web: filter incoming by per-browser peerID, not source label

Old filter hid all source=web messages — meant multiple browsers
couldn't see each other's sends. Now each browser only filters out
its OWN peerID, so iphone↔mbp↔desktop all see each other's clipboard.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

server/web/index.html

@@ -147,7 +147,7 @@
         const r = await fetch("/api/send", {
           method: "POST",
           headers: { "Content-Type": "application/json" },
-          body: JSON.stringify({ type: "clipboard", text, source: "web" }),
+          body: JSON.stringify({ type: "clipboard", text, source: "web", from: peerID }),
         });
         status(r.ok ? "delivered ✓" : "server returned " + r.status, r.ok ? "ok" : "err");
       } catch (e) { status("network error", "err"); }
@@ -207,7 +207,7 @@
     es.addEventListener("clipboard", (ev) => {
       try {
         const m = JSON.parse(ev.data);
-        if (m.source !== "web") {
+        if (m.from !== peerID) {     // hide our own sends, show everyone else
           addIncoming(m.text, m.source, m.ts, false);
         }
       } catch (e) {}