feat(panel): edit memoryMB from the Settings modal

Adds GET/POST /api/daemon/config (safe subset of server-config.json --
just memoryMB for now) and a "Resources" section in the existing Settings
modal. The Save and Save+restart buttons now POST both /api/server/settings
and /api/daemon/config; restartRequired is OR'd across the two endpoints.

Future fields like backupKeep / backupSchedule / bluemapDir can be added
by extending DAEMON_FIELDS in settings.js + the validation block in
RunCommand.cs. Sensitive fields (passwords, manifestUrl, ports) are
intentionally kept off this endpoint.

server/wwwroot/styles.css

@@ -382,6 +382,14 @@ button.ghost-btn {
 .card.collapsible:not(.expanded) h2 { margin: 0; }
 
 /* Server settings modal */
+.settings-section-label {
+    font-size: 11px;
+    font-weight: 600;
+    letter-spacing: 0.05em;
+    text-transform: uppercase;
+    color: var(--text-muted);
+    margin-bottom: 8px;
+}
 .settings-grid {
     display: grid;
     grid-template-columns: 1fr 1fr;