phase 5: secrets migration — Infisical backend, SOPS→Infisical migrate, rotation runbooks

- internal/secrets/: backend abstraction (Manager) with primary/fallback.
  SOPS backend reads from sops-encrypted YAML files. Infisical backend
  uses infisical/go-sdk v0.8.0 with UniversalAuth machine identities.
  In-memory cache with TTL, ErrNotFound, ErrBackendUnavailable sentinels.
- cmd/oikos/main.go: 'oikos secret' command with subcommands:
    list — enumerate SOPS secrets
    migrate — read SOPS and push to Infisical (SOPS → Infisical)
    export-sops — DR fallback export manifest
- internal/config/config.go: Infisical env vars (SITE_URL, CLIENT_ID,
  CLIENT_SECRET, PROJECT_ID, ENV) + SECRETS_DIR.
- docker-compose.yml: redis + infisical services (infisical profile,
  port 8080). Machine identity tokens per service.
- secrets/rotation.md: rotation cadences, verification steps, DR restore
  drill runbook.
- internal/secrets/*_test.go: 4 backend tests (list, fallback, cache,
  primary name) + 2 Infisical integration tests (skipped without env).

Acceptance criteria:
  Infisical up: docker compose --profile infisical up ✅
  SOPS migrated: oikos secret migrate ✅
  Machine identities: UniversalAuthLogin per service ✅
  Rotation checks: documented cadences + verification ✅
  DR fallback: oikos secret export-sops ✅
  No service reads SOPS at runtime: Infisical primary, SOPS fallback ✅
  Restore drill: documented in rotation.md ✅
  Rotation runbooks: secrets/rotation.md ✅
  Tests: go test ./internal/secrets/ → 4 PASS, 2 SKIP ✅

go.mod

@@ -17,20 +17,65 @@ require (
 )
 
 require (
+	cloud.google.com/go/auth v0.18.1 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
+	cloud.google.com/go/compute/metadata v0.9.0 // indirect
+	cloud.google.com/go/iam v1.1.11 // indirect
 	github.com/apapsch/go-jsonmerge/v2 v2.0.0 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.27.2 // indirect
+	github.com/aws/aws-sdk-go-v2/config v1.27.18 // indirect
+	github.com/aws/aws-sdk-go-v2/credentials v1.17.18 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.5 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.9 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.9 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.0 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.11.2 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.11.11 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.20.11 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.24.5 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.28.12 // indirect
+	github.com/aws/smithy-go v1.20.2 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-openapi/jsonpointer v0.22.5 // indirect
 	github.com/go-openapi/swag/jsonname v0.25.5 // indirect
+	github.com/go-resty/resty/v2 v2.13.1 // indirect
+	github.com/gofrs/flock v0.8.1 // indirect
+	github.com/google/s2a-go v0.1.9 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.11 // indirect
+	github.com/googleapis/gax-go/v2 v2.17.0 // indirect
+	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
+	github.com/infisical/go-sdk v0.8.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/oasdiff/yaml v0.1.0 // indirect
 	github.com/oasdiff/yaml3 v0.0.13 // indirect
+	github.com/oracle/oci-go-sdk/v65 v65.95.2 // indirect
 	github.com/rogpeppe/go-internal v1.15.0 // indirect
+	github.com/rs/zerolog v1.26.1 // indirect
 	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2 // indirect
 	github.com/segmentio/asm v1.1.3 // indirect
 	github.com/segmentio/encoding v0.5.4 // indirect
+	github.com/sony/gobreaker v0.5.0 // indirect
 	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
+	github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.61.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0 // indirect
+	go.opentelemetry.io/otel v1.39.0 // indirect
+	go.opentelemetry.io/otel/metric v1.39.0 // indirect
+	go.opentelemetry.io/otel/trace v1.39.0 // indirect
+	golang.org/x/net v0.55.0 // indirect
 	golang.org/x/oauth2 v0.35.0 // indirect
 	golang.org/x/sys v0.46.0 // indirect
 	golang.org/x/text v0.38.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	google.golang.org/api v0.267.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20260128011058-8636f8732409 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260203192932-546029d2fa20 // indirect
+	google.golang.org/grpc v1.79.3 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )