feat: add charts, world map, and filters to web dashboard

Add Chart.js line/bar charts for attack trends (attempts over time,
hourly pattern), an SVG world map choropleth colored by attack origin
country, and a collapsible filter form (date range, IP, country,
username) that narrows both charts and top-N tables.

New store methods: GetAttemptsOverTime, GetHourlyPattern, GetCountryStats,
and filtered variants of dashboard stats/top-N queries. New JSON API
endpoints at /api/charts/* and an htmx fragment at
/fragments/dashboard-content for filtered table updates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/web/templates/layout.html

@@ -36,6 +36,9 @@
             overflow: hidden;
             min-width: 0;
         }
+        #world-map svg { width: 100%; height: auto; }
+        #world-map svg path { fill: #2a2a3e; stroke: #555; stroke-width: 0.5; transition: fill 0.2s; }
+        #world-map svg path:hover { stroke: #fff; stroke-width: 1; }
         nav h1 {
             margin: 0;
         }
@@ -56,5 +59,6 @@
     <main class="container">
         {{block "content" .}}{{end}}
     </main>
+    {{block "scripts" .}}{{end}}
 </body>
 </html>