feat(settings): unified server-URL resolver + field; adopt in Jellyseerr

Type a loose address (media.example.com, https://…, host:port) and the app finds the working, canonical URL.

- utils/serverUrl: generic candidate generator (https-first, port/path preserved, no Jellyfin-specific ports), parallel-probe resolver, numeric semver compare, and a Jellyseerr probe (/api/v1/status, min 2.0.0).

- useServerUrlResolver: idle -> resolving -> ok | error state machine with cancellation.

- ServerUrlField: shared input that auto-resolves on blur, inline status chip (tap to re-test) + resolved URL, persists the canonical URL.

- Jellyseerr settings adopt the field and log in with the resolved URL. Probe contract makes Streamystats/Jellyfin/Merlin a drop-in follow-up.

utils/serverUrl/probes/jellyseerr.ts

@@ -0,0 +1,41 @@
+import axios from "axios";
+import { isVersionBelow } from "../semver";
+import type { ServerProbe } from "../types";
+
+/** Jellyseerr/Overseerr minimum supported version. */
+const MIN_VERSION = "2.0.0";
+
+/**
+ * Probe for a Jellyseerr server. `/api/v1/status` is jellyseerr/overseerr
+ * specific and unauthenticated, so it both proves reachability and confirms
+ * we hit the right service.
+ */
+export const jellyseerrProbe: ServerProbe = async (url, signal) => {
+  try {
+    const { status, data } = await axios.get(`${url}/api/v1/status`, {
+      signal,
+      timeout: 8000, // backstop; the resolver aborts via signal first
+    });
+
+    if (status < 200 || status >= 300) return { status: "unreachable" };
+
+    const version: string | undefined =
+      typeof data?.version === "string" ? data.version : undefined;
+
+    // A JSON body carrying version/commitTag identifies a real jellyseerr.
+    if (
+      !version &&
+      !(data && typeof data === "object" && "commitTag" in data)
+    ) {
+      return { status: "wrong-service" };
+    }
+
+    if (version && isVersionBelow(version, MIN_VERSION)) {
+      return { status: "version-too-low", version };
+    }
+
+    return { status: "ok", meta: { version } };
+  } catch {
+    return { status: "unreachable" };
+  }
+};