Refactor settings modal to use ISettingsModalService and SettingsModalSections

- Replace SettingsModalContext with SettingsModalSections
- Add SettingsModalService for modal state management
- Add StatusSection.razor.css for status-dot styles
- Update layout, NavMenu, and modal components
- Update tests for config/settings changes

testdata/dnsmasq-test.conf

@@ -1,4 +1,4 @@
-# Config for the dnsmasq test container only (docker-compose.test.yml).
+# Config for the dnsmasq test container only (docker-compose.test.yml).
 # DNS + DHCP: forwards DNS to Cloudflare/Google with caching; hands out DHCP on testnet.
 # Uses same testdata layout so app and dnsmasq share hosts, dhcp.conf, leases.
 # Richer config so UI shows multi-value lists (server, addn-hosts, address, dhcp-range) and readonly sources.
@@ -32,5 +32,3 @@ addn-hosts=/data/hosts.extra
 # Log to file so the harness can show real logs (LogsCommand tails this)
 log-facility=/data/dnsmasq.log
 log-queries
-
-conf-file=zz-dnsmasq-webui.conf