Surface structured RCON failure reasons in the fleet UI

rconGetStatus previously collapsed at least five distinct failure modes
(no password, no port, socket error, timeout, bad reply) into a single
null return, so the UI could only say "rcon unreachable" — useless when
diagnosing a real Alcatraz outage.

Refactored to rconStatusResult() returning a discriminated union with a
RconFailure reason and human-facing detail. The worker persists these as
"<reason>:<detail>" in last_error (no schema change). /api/servers now
returns the derived endpoint (host:port) per server plus a top-level
integrations block (rcon/komodo configured, timeout, default host).

Server detail page gains an RCON diagnostic panel when health is not
online: shows the exact endpoint being dialed, integration status,
timeout, a color-coded reason tag, the detail, and a targeted fix hint.
Wrong-password replies are detected via "bad rcon" text in the print
body.

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

src/lib/ui/stores/servers.ts

@@ -10,6 +10,12 @@ export interface RosterPlayer {
 }
 
 export type Health = 'online' | 'stale' | 'offline';
+export type RconFailure = 'no-config' | 'no-port' | 'send-error' | 'timeout' | 'bad-reply' | 'no-players';
+
+export interface RconEndpoint {
+    host: string;
+    port: number;
+}
 
 export interface ServerStatus {
     server: string;
@@ -20,6 +26,8 @@ export interface ServerStatus {
     health: Health;
     lastSeenAt: string | null;
     lastError: string | null;
+    endpoint: RconEndpoint | null;
+    reason: RconFailure | null;
 }
 
 export const statusByServer = writable<Map<string, ServerStatus>>(new Map());