Refactor architecture: extract reconciler, add interfaces, reduce complexity, improve test coverage

Architecture:
- Extract reconcileNetworking into internal/reconcile package with 7 consumer-side interfaces
- Add locked modifyState helper to fix state.yaml read-modify-write race condition
- Extract CrowdSec and VPN handler groups with interfaces documenting dependency surface
- Replace raw map[string]any YAML manipulation with typed AddDHCPStaticLease/RemoveDHCPStaticLease
- Extract Cloudflare API functions into cfClient struct, eliminating repeated auth boilerplate

Complexity reduction:
- haproxy.GenerateWithOpts: 50 → 6 (extracted 8 focused helpers)
- reconcile.Reconcile: 42 → 11 (extracted buildRoutes, buildDNSEntries, writeHAProxyConfig)
- AutheliaUpdateConfig: 25 → 10 (extracted enableAuthelia/disableAuthelia)

Test coverage improvements:
- reconcile: 4.5% → 56.8% (stub-based tests for route building, DNS entries, orchestration)
- dnsfilter: 10.7% → 45.6% (Manager.Compile, AddList, ToggleList, custom entries)
- config: 67.3% → 89.8% (DHCP static lease mutation tests)

internal/dnsmasq/config_test.go

@@ -266,9 +266,9 @@ func TestGenerate_MixedDomains(t *testing.T) {
 	globalCfg := &config.State{}
 
 	entries := []DNSEntry{
-		wildcardEntry("cloud.payne.io", "192.168.8.240"),  // wildcard
-		entry("central.payne.io", "192.168.8.151"),         // exact
-		entry("wild-cloud.payne.io", "192.168.8.151"),      // exact
+		wildcardEntry("cloud.payne.io", "192.168.8.240"), // wildcard
+		entry("central.payne.io", "192.168.8.151"),       // exact
+		entry("wild-cloud.payne.io", "192.168.8.151"),    // exact
 	}
 
 	out := g.Generate(globalCfg, entries)