Make the resolver pure DNS: JSON access log on stdout instead of a log store

The resolver kept its own query-log store (a bbolt ring, a live ring with SSE
fanout, rolling per-domain counters and dashboard time-series) for the console.
In a multi-node deployment each pod held a different slice of that, so every
view disagreed with itself, and the cost sat on the query path. Charts belong
in Grafana and log search in the log collector, so the store is gone.

internal/accesslog writes one JSON line per notable query to stdout. The default
is what was blocked and what failed (blocked, redirected, SERVFAIL, dropped,
refused); log_cached and sample_rate add ordinary answers for a debugging
session. Lines go through a bounded buffer to a single writer goroutine and are
dropped, and counted in fancydns_access_log_dropped_total, when the stream
cannot keep up, so a stalled log pipe can never stall a query. The config key is
access_log (the old qlog block is ignored, like any unknown key).

The metrics gain what the dashboard used to compute: fancydns_group_queries_total
by ACL group and outcome and fancydns_responses_total by RCODE. Removed with the
store: /api/dashboard, /api/logs, /api/logs/stream, /api/logs/clear,
/api/cache/top, the series rings, and the cache's per-name hit table, which took
a mutex and built a string on every cache hit.

Tests that read the old log now read the access-log lines; the contract test
drops the removed endpoints. The web console still calls them and is changed in
the next commit.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/api/harness_test.go

@@ -48,19 +48,14 @@ type fakeHooks struct {
 
 	// arguments the API passed down, for the routes where the argument is
 	// the interesting part of the contract.
-	dashRange   []string
 	domainQuery []DomainQuery
 	domainAdd   []DomainInput
 	domainDel   []domainDelete
 	aclPut      []aclPut
 	upstreamPut []config.Upstream
-	logQuery    []LogQuery
 	refresh     [][]string
 	toggle      []toggleCall
-	cacheTop    []int
-	clearLog    int
 	flushes     int
-	logStats    int
 
 	// fail maps a hook name to the error it should return, so the error
 	// branches of a handler can be reached without a real component.
@@ -68,12 +63,6 @@ type fakeHooks struct {
 	// panicOn names hooks that panic instead of returning, which is how the
 	// recoverer gets exercised.
 	panicOn map[string]bool
-
-	// stream plumbing for the SSE test.
-	stream    chan LogEntry
-	unsub     chan struct{}
-	unsubOnce sync.Once
-	subs      int
 }
 
 type domainDelete struct {
@@ -96,8 +85,6 @@ func newFakeHooks() *fakeHooks {
 	return &fakeHooks{
 		fail:    map[string]error{},
 		panicOn: map[string]bool{},
-		stream:  make(chan LogEntry, 16),
-		unsub:   make(chan struct{}),
 	}
 }
 
@@ -174,10 +161,6 @@ func (f *fakeHooks) reset() {
 
 func (f *fakeHooks) hooks() Hooks {
 	return Hooks{
-		Dashboard: func(_ context.Context, rangeKey string) (any, error) {
-			f.record("Dashboard", func() { f.dashRange = append(f.dashRange, rangeKey) })
-			return map[string]any{"range": rangeKey}, f.err("Dashboard")
-		},
 		BlocklistState: func() any {
 			f.record("BlocklistState", func() {})
 			return map[string]any{"lists": []any{}}
@@ -254,40 +237,10 @@ func (f *fakeHooks) hooks() Hooks {
 			f.record("PutUpstream", func() { f.upstreamPut = append(f.upstreamPut, up) })
 			return 43, f.err("PutUpstream")
 		},
-		SearchLog: func(_ context.Context, q LogQuery) (any, error) {
-			f.record("SearchLog", func() { f.logQuery = append(f.logQuery, q) })
-			return map[string]any{"entries": []any{}}, f.err("SearchLog")
-		},
-		LogStats: func() any {
-			f.mu.Lock()
-			f.logStats++
-			f.mu.Unlock()
-			return map[string]any{"qps": 1}
-		},
-		SubscribeLog: func() (<-chan LogEntry, func()) {
-			f.mu.Lock()
-			f.subs++
-			f.calls = append(f.calls, "SubscribeLog")
-			f.mu.Unlock()
-			return f.stream, func() {
-				f.mu.Lock()
-				f.subs--
-				f.mu.Unlock()
-				f.unsubOnce.Do(func() { close(f.unsub) })
-			}
-		},
-		ClearLog: func() error {
-			f.record("ClearLog", func() { f.clearLog++ })
-			return f.err("ClearLog")
-		},
 		CacheStats: func() any {
 			f.record("CacheStats", func() {})
 			return map[string]any{"entries": 0}
 		},
-		CacheTop: func(limit int) any {
-			f.record("CacheTop", func() { f.cacheTop = append(f.cacheTop, limit) })
-			return []any{}
-		},
 		FlushCache: func() int64 {
 			f.record("FlushCache", func() { f.flushes++ })
 			return 0
@@ -304,20 +257,6 @@ func (f *fakeHooks) hooks() Hooks {
 	}
 }
 
-// subscribers is the number of live SSE subscribers; it must be back to zero
-// once a client has disconnected.
-func (f *fakeHooks) subscribers() int {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-	return f.subs
-}
-
-func (f *fakeHooks) statsCalls() int {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-	return f.logStats
-}
-
 // harness is a wired Server behind an httptest listener, with a config file on
 // disk so the settings and reload routes have something real to work on.
 type harness struct {