add ad blocking, live dashboard, system DNS auto-discovery

- DNS-level ad blocking: 385K+ domains via Hagezi Pro blocklist, subdomain
  matching, one-click allowlist, pause/toggle, background refresh every 24h
- Live dashboard at :5380 with real-time stats, query log, override
  management (create/edit/delete), blocking controls
- System DNS auto-discovery: parses scutil --dns on macOS to find
  conditional forwarding rules (Tailscale, VPN split-DNS)
- REST API expanded to 18 endpoints (blocking, overrides, diagnostics)
- Startup banner with colored system info
- Performance benchmarks (bench/dns-bench.sh)
- Landing page updated with new positioning and comparison table
- CI, Dockerfile, LICENSE, development plan docs

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

src/lib.rs

@@ -1,12 +1,18 @@
+pub mod api;
+pub mod blocklist;
 pub mod buffer;
 pub mod cache;
 pub mod config;
+pub mod ctx;
 pub mod forward;
 pub mod header;
+pub mod override_store;
 pub mod packet;
+pub mod query_log;
 pub mod question;
 pub mod record;
 pub mod stats;
+pub mod system_dns;
 
 pub type Error = Box<dyn std::error::Error + Send + Sync>;
 pub type Result<T> = std::result::Result<T, Error>;