ctcloud: CertSpotter-backed CT cloud-resource monitor

Single stateless Go process that consumes CT logs via embedded (patched)
CertSpotter internals, classifies cloud/database/storage DNS identifiers
in-process with a zero-allocation classifier, enriches via round-robin DNS
resolvers with CNAME following, and batch-writes useful findings to PostgreSQL.

- third_party/certspotter: 2-hunk IdentifierSink patch, no stdout/JSON/files
- internal/classify: AWS/Azure/GCP/Firebase/Cloudflare R2/DigitalOcean/Supabase/OCI
- internal/dns: sharded bounded TTL cache, multi-resolver load balancing + failover
- internal/pipeline: bounded queues, dedup, direct-priority load shedding
- internal/store: pgx batch writer, Postgres CT checkpoints (no cert contents)
- internal/probe: optional non-destructive reachability checks (off by default)
- Docker: distroless non-root, read-only rootfs, no app volume, resource limits
- tests enforce 0 allocs/op on the classifier and sink hot path

.dockerignore

@@ -0,0 +1,6 @@
+.git
+.gitignore
+pgdata
+*.test
+*.out
+.gocache