feat: add analytics dashboard with traffic monitoring

- Parse Caddy access logs every 30s into traffic_events SQLite table
- GeoIP country lookup via maxmind (GeoLite2-Country.mmdb)
- 90-day retention with automatic purge
- Analytics page with interval (24h/7d/30d) and per-host filtering:
  - Stats cards: total requests, unique IPs, blocked count, block rate
  - Requests-over-time area chart (ApexCharts)
  - SVG world choropleth map (d3-geo + topojson-client, React 19 compatible)
  - Top countries table with flag emojis
  - HTTP protocol donut chart
  - Top user agents horizontal bar chart
  - Recent blocked requests table with pagination
- Traffic (24h) summary card on Overview page linking to analytics
- 7 authenticated API routes under /api/analytics/
- Share caddy-logs volume with web container (read-only)
- group_add caddy GID to web container for log file read access

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

app/(dashboard)/DashboardLayoutClient.tsx

@@ -27,6 +27,7 @@ import ShieldIcon from "@mui/icons-material/Shield";
 import SettingsIcon from "@mui/icons-material/Settings";
 import HistoryIcon from "@mui/icons-material/History";
 import LogoutIcon from "@mui/icons-material/Logout";
+import BarChartIcon from "@mui/icons-material/BarChart";
 
 type User = {
   id: string;
@@ -37,6 +38,7 @@ type User = {
 
 const NAV_ITEMS = [
   { href: "/", label: "Overview", icon: DashboardIcon },
+  { href: "/analytics", label: "Analytics", icon: BarChartIcon },
   { href: "/proxy-hosts", label: "Proxy Hosts", icon: DnsIcon },
   { href: "/access-lists", label: "Access Lists", icon: SecurityIcon },
   { href: "/certificates", label: "Certificates", icon: ShieldIcon },