Bind to 0.0.0.0 and use dynamic Host header for bookmarklet

Makes the server accessible from other devices on the network
instead of only localhost. The bookmarklet now uses the Host header
from the request so it works regardless of how the server is accessed.

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

app.py

@@ -505,7 +505,7 @@ class Handler(BaseHTTPRequestHandler):
             f"</form>"
             f"<h2>bookmarklet</h2>"
             f"<p>Drag this link to your bookmarks bar. Click it on any page to index it instantly.</p>"
-            f'<p><a href="javascript:void(fetch(\'http://localhost:5001/bookmark?url=\'+encodeURIComponent(location.href)).then(r=>r.text()).then(t=>alert(t)).catch(()=>alert(\'tinyweb not running\')))">+ save to {esc(name)}</a></p>'
+            f'<p><a href="javascript:void(fetch(\'http://{esc(self.headers.get("Host", "localhost:5001"))}/bookmark?url=\'+encodeURIComponent(location.href)).then(r=>r.text()).then(t=>alert(t)).catch(()=>alert(\'tinyweb not running\')))">+ save to {esc(name)}</a></p>'
             f"<p>{msg}</p>"
             f'<a href="/">back</a>'
         )
@@ -520,5 +520,5 @@ class Handler(BaseHTTPRequestHandler):
 
 if __name__ == "__main__":
     init_db()
-    print("running on http://localhost:5001")
-    HTTPServer(("localhost", 5001), Handler).serve_forever()
+    print("running on http://0.0.0.0:5001")
+    HTTPServer(("0.0.0.0", 5001), Handler).serve_forever()