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- Hub rejects nodes older than 0.5.0 (close 4026), /ui/nodes reports outdated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/migrate/migrate.css

@@ -0,0 +1,25 @@
+/*
+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.
+*/
+/* Стили вкладки «Перенос». Общая дизайн-система — в App.css. */
+
+.mv-box { display: flex; flex-direction: column; gap: 10px; background: var(--surface-container); border-radius: var(--shape-large); padding: 12px 16px; }
+.mv-title { margin: 0; font-size: var(--title-small-size); line-height: var(--title-small-line); font-weight: var(--weight-medium); }
+.mv-text { margin: 0; font-size: var(--body-medium-size); line-height: 1.5; }
+.mv-muted { font-size: var(--body-small-size); line-height: var(--body-small-line); color: var(--neutral-text); }
+.mv-steps { margin: 0; padding-left: 20px; font-size: var(--body-medium-size); line-height: 1.6; }
+.mv-row { display: flex; gap: 8px; }
+.mv-row .field { flex: 1; min-width: 0; font-family: var(--mono); font-size: var(--body-small-size); line-height: var(--body-small-line); }
+.mv-row--end { justify-content: flex-end; flex-wrap: wrap; }
+.mv-self { align-self: flex-start; }
+.mv-notice {
+    font-size: var(--body-medium-size); line-height: var(--body-medium-line); color: var(--on-error-container); background: var(--error-container);
+    border-radius: var(--shape-large); padding: 10px 16px; margin: 0;
+}
+.mv-box .node-modal-cmd { background: var(--surface-bright); }
+@media (max-width: 599px) { .mv-row:not(.mv-row--end) { flex-direction: column; } }
+.mv-checks { display: flex; flex-direction: column; gap: 8px; }
+.mv-check { display: flex; align-items: baseline; gap: 10px; font-size: var(--body-medium-size); line-height: 1.5; }
+.mv-check .chip { flex-shrink: 0; }