feat: claude-code backends, llamaswap provider, dogfood the CC engine

Phase 2 of the gadfly-games build.

- Bump majordomo to the latest build and wire its new **llamaswap**
  provider into gadfly's endpoint switches (GADFLY_PROVIDER=llamaswap +
  GADFLY_BASE_URL, and GADFLY_ENDPOINT_<NAME>="llamaswap|url[|key]"),
  mirroring the ollama provider. Wired but untested (no llama-swap here).
- Dogfood the Phase-1 claude-code engine: add `claude-code/sonnet` to
  gadfly's own review swarm as a competitor alongside the 9 cloud models
  + M5, pin the workflow to :sha-86f12c1 (the image that bundles the
  claude CLI), and map CLAUDE_CODE_OAUTH_TOKEN. Its own provider lane
  (claude-code=1), parallel with the cloud and m5 lanes.
- Document the alternate Claude Code backends: Pro/Max (default), and —
  EXAMPLE ONLY, not wired — running Ollama models THROUGH the CC harness
  via ANTHROPIC_BASE_URL pointed at an Anthropic-compatible proxy
  (claude-code-router / LiteLLM). The subprocess env already forwards
  ANTHROPIC_*/CLAUDE_*, so no code change is needed for that path.
- README: llamaswap row in the providers table + a Claude Code
  "alternate backends" note; examples/claude-code.yml shows the proxy env.

gofmt clean, go vet quiet, go build + go test -race green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

go.mod

@@ -3,26 +3,35 @@ module gitea.stevedudenhoeffer.com/steve/gadfly
 go 1.26.2
 
 require (
-	gitea.stevedudenhoeffer.com/steve/majordomo v0.0.0-20260610113006-0147a79d187b
+	gitea.stevedudenhoeffer.com/steve/majordomo v0.0.0-20260627201401-b2487a1a370c
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
-	cloud.google.com/go v0.116.0 // indirect
-	cloud.google.com/go/auth v0.9.3 // indirect
-	cloud.google.com/go/compute/metadata v0.5.0 // indirect
-	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
-	github.com/google/go-cmp v0.6.0 // indirect
-	github.com/google/s2a-go v0.1.8 // indirect
-	github.com/googleapis/enterprise-certificate-proxy v0.3.4 // indirect
+	cloud.google.com/go v0.123.0 // indirect
+	cloud.google.com/go/auth v0.20.0 // indirect
+	cloud.google.com/go/compute/metadata v0.9.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/felixge/httpsnoop v1.1.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/google/s2a-go v0.1.9 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.17 // indirect
+	github.com/googleapis/gax-go/v2 v2.22.0 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
-	go.opencensus.io v0.24.0 // indirect
-	golang.org/x/crypto v0.36.0 // indirect
-	golang.org/x/net v0.38.0 // indirect
-	golang.org/x/sys v0.31.0 // indirect
-	golang.org/x/text v0.23.0 // indirect
-	google.golang.org/genai v1.59.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1 // indirect
-	google.golang.org/grpc v1.66.2 // indirect
-	google.golang.org/protobuf v1.34.2 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.69.0 // indirect
+	go.opentelemetry.io/otel v1.44.0 // indirect
+	go.opentelemetry.io/otel/metric v1.44.0 // indirect
+	go.opentelemetry.io/otel/trace v1.44.0 // indirect
+	golang.org/x/crypto v0.53.0 // indirect
+	golang.org/x/net v0.56.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
+	golang.org/x/text v0.38.0 // indirect
+	google.golang.org/api v0.286.0 // indirect
+	google.golang.org/genai v1.62.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260622175928-b703f567277d // indirect
+	google.golang.org/grpc v1.81.1 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )