Refactor parsers to Superpower; config set; EnsureManagedConfig; options doc

- Parsers: Superpower for all (Directive, FileLine, Include, DhcpHost, Leases, Hosts)
- Shared ConfParserHelpers (Token, OptionalCommentPrefix)
- DnsmasqConfOptionRegistry + DnsmasqOptionKind: typed options (ConfFile, ConfDir,
  Domain, DhcpRange, Server, Local, Address, DhcpOption, DhcpHost, Path, Flag, etc.)
- EnsureManagedConfigHostedService: append conf-dir= to main config if missing,
  then create managed file; DnsmasqOptions + Dockerfile comments for permissions
- Renames: ConfigLine->DnsmasqConfLine, ConfigSet->DnsmasqConfigSet, etc.
- Test harness: entrypoint in scripts/, prepare-test-mount improvements
- Status/Reload API and UI: stdout+stderr, exit code

docker-compose.test.yml

@@ -17,9 +17,9 @@ services:
       - NET_ADMIN
     environment:
       DNSMASQ_CONF: /data/dnsmasq-test.conf
+      Dnsmasq__MainConfigPath: /data/dnsmasq-test.conf
+      Dnsmasq__ManagedFileName: zz-dnsmasq-webui.conf
       Dnsmasq__HostsPath: /data/hosts
-      Dnsmasq__ConfigPath: /data/dnsmasq.d/dhcp.conf
-      Dnsmasq__LeasesPath: /data/leases
       Dnsmasq__ReloadCommand: "pkill -HUP -x dnsmasq"
       Dnsmasq__StatusCommand: "pgrep -x dnsmasq"
     volumes: