a11y: Web Interface Guidelines — 19 правок доступности и семантики

- base.html: lang динамический, meta theme-color, skip-link, убран дубль Dashboard
- Фильтры: labels на search/select, type=search, placeholder с …, autocomplete=off
- llm-retry: <span> → <button> во всех шаблонах (_llm_report, scan, package)
- sortable th: tabindex=0, role=button через JS + keyboard handler
- sort-icon: aria-hidden=true
- style.css: color-scheme:dark, prefers-reduced-motion, tabular-nums, touch-action
- app.js: clipboard fallback для не-HTTPS

guarddog_nexus/web/templates/dashboard_stats.html

@@ -1,5 +1,5 @@
 {% if total_findings %}
-<div style="display:flex; gap:1.5rem; padding:0.3rem 0; margin-bottom:1rem; border-bottom:1px solid var(--pico-color-gray-500); font-size:0.82rem; opacity:0.8; flex-wrap:wrap;">
+<div style="display:flex; gap:1.5rem; padding:0.3rem 0; margin-bottom:1rem; border-bottom:1px solid #2a3140; font-size:0.82rem; opacity:0.8; flex-wrap:wrap;">
     <span>{{ t('total_scans_label', request.state.lang) }}: <strong>{{ total_scans }}</strong></span>
     <span>{{ t('flagged_scans_label', request.state.lang) }}: <strong>{{ flagged_scans }}</strong></span>
     <span>{{ t('col_findings', request.state.lang) }}: <strong>{{ total_findings }}</strong></span>