Panel redesign, per-server I1 masking, node minimum version 0.5.0, installer output

- UI: settings tab with sections (server, API keys, Prometheus, audit, migrate,
  about); server settings moved there; master keys table rework (menu, chips,
  version, compact phone cards); three-state node version chip
- I1: random per-server template (DNS / QUIC Initial / STUN) kept in users.db,
  GET/POST /api/masking, change from the master keys banner
- Hub rejects nodes older than 0.5.0 (close 4026), /ui/nodes reports outdated
- install.sh: spinner for long commands (full output in the log), step progress
  bar, cards; installs older than 0.5.0 require a full reinstall with data reset
- Bump to Beta 0.5.0

awg-ui/src/tabs/settings/server/server.css

@@ -0,0 +1,11 @@
+/*
+Copyright (c) 2026 Ivan Vasilev
+This source code is licensed under the MIT license found in the
+LICENSE file in the root directory of this source tree.
+*/
+/* Раздел «Сервер» вкладки «Настройки»: бывший диалог «Настройки сервера», строки .ss-* — из App.css */
+.ss-card { gap: 12px; padding: 16px; }
+.ss-card .ss-section { margin: 0; }
+.ss-card .ss-status { background: var(--surface-container-lowest); }
+.ss-actions { display: flex; justify-content: flex-end; }
+.ss-card .ss-grid { max-width: 480px; }