Test each pipeline stage in isolation through resolve_query:
- override takes precedence over all other paths
- localhost and *.localhost resolve to loopback
- local zone returns configured records
- .tld proxy resolves registered services to loopback
- blocklist sinkholes to 0.0.0.0
- cache hit returns stored response without upstream
resolve_query now returns (BytePacketBuffer, QueryPath) so callers
and tests can inspect the resolution path without reading the query
log. Production call sites (UDP, DoT, DoH) destructure and ignore it.
The forwarding test now uses a mock UDP upstream that replies with a
canned response, asserting QueryPath::Forwarded instead of != Local.
Explicit [[forwarding]] rules now take precedence over the RFC 6303
special-use domain intercept. Previously, PTR queries for private
ranges (e.g. 168.192.in-addr.arpa) always returned local NXDOMAIN
even when a forwarding rule pointed them at a corporate DNS server.
Add full-pipeline resolve_query test harness (test_ctx + resolve_in_test)
and two tests covering both the default behavior and the override.
Closes#94
