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/types.ts

@@ -0,0 +1,16 @@
+/** Result of probing a single candidate URL for a specific service. */
+export type ServerProbeOutcome =
+  | { status: "ok"; meta?: Record<string, unknown> }
+  | { status: "version-too-low"; version?: string }
+  | { status: "wrong-service" }
+  | { status: "unreachable" };
+
+/**
+ * Validates one fully-qualified candidate URL for a given service.
+ * Implementations must resolve (never reject) — map errors to "unreachable".
+ * The provided signal is aborted on timeout or cancellation.
+ */
+export type ServerProbe = (
+  url: string,
+  signal: AbortSignal,
+) => Promise<ServerProbeOutcome>;