feat(webview): open localhost links through a proxied web tab from another device

An agent prints `http://localhost:5173/` (a dev server, a preview it just
served) and the user taps it on a phone. That address only exists on the
Codeman box, so the link was a guaranteed connection error from any other
device — while the web-tab proxy fetches from the server, where it works.

A loopback link (`localhost`, `*.localhost`, 127/8, 0.0.0.0, ::1) activated
in the terminal or clicked in the Response Viewer now opens as a proxied
web tab whenever the Codeman page itself is not on that box. A saved
proxied dashboard on the same origin is reused, with the link's own path,
query and fragment opened inside it (a mounted frame is navigated, not torn
down, so its state survives); otherwise one is saved under its host:port,
sandboxed like any other web tab, so it is in the Run dropdown next time.

Only loopback is routed this way. A LAN or tailnet address may well be
reachable from the device (a VPN, the same Wi-Fi) and a direct open is the
cheaper, richer path, so those keep opening in a new browser tab; on the
box itself every link opens directly. The terminal link provider and the
viewer's click handler consult one hook and fall through to their existing
behaviour when it declines.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01McLWqCWBuQYGuPMScb4Aou

src/web/public/app.js

@@ -2149,6 +2149,16 @@ class CodemanApp {
         return;
       }
 
+      // A `localhost` URL in the agent's answer: from another device that can
+      // only load through the server, so hand it to a proxied web tab
+      // (webview-tabs.js). Every other link keeps its new-tab default.
+      const urlLink = ev.target.closest('a[href]');
+      if (urlLink && this.openLinkThroughWebTabIfLoopback?.(urlLink.href)) {
+        ev.preventDefault();
+        ev.stopPropagation();
+        return;
+      }
+
       // One-click copy: lift the raw source from the sibling <pre><code>.
       const copyBtn = ev.target.closest('.rv-copy-btn');
       if (copyBtn) {