Add resource attribute support to ChipIngress client

[pkcll]

Summary

• Adds resource-attribute propagation from beholder.Config.ResourceAttributes to the ChipIngress cre topic via two mechanisms: (1) gRPC metadata headers (chipingress.WithHeaderProvider/NewStaticHeaderProvider), raw key names, parity with beholder__platform__messages; (2) CloudEvent extensions (chipingress.WithResourceAttributeExtensions) with keys sanitized to ^[a-z0-9]+$ per the CloudEvents spec, surfacing as ce_<name> Kafka headers.
• Wires both the non-batch ChipIngressEmitter and ChipIngressBatchEmitterService to stamp resource attributes on every emitted event.

Known gaps / follow-ups (called out for reviewers)

• gRPC-metadata → Kafka-header forwarding is unconfirmed server-side. The chip-ingress server's baseKafkaHeaders logic does not appear to forward arbitrary incoming gRPC metadata onto Kafka headers today. The CE-extension mechanism guarantees headers immediately; the gRPC-metadata mechanism is shipped for observability now, with full parity once/if a chip-ingress server-side change forwards it. A follow-up ticket against chip-ingress should track that.
• pkg/durableemitter is out of scope. It has its own NewEvent call site and config, and wiring it up would also require chainlink core changes (application.go, shell.go, plugins/loop_registry.go). This assumes production CRE-topic traffic goes through the beholder emitters, not DurableEmitter — unconfirmed, worth a sanity check before merge.
• Cross-module version bump needed. pkg/chipingress is its own Go module; go.mod's pinned pkg/chipingress pseudo-version needs bumping to pick these changes up in pkg/beholder (standard two-step process per this repo's history).

Test plan

• go test ./pkg/chipingress/... and go test ./pkg/beholder/... pass
• New unit tests: SanitizeExtensionName, WithResourceAttributeExtensions (sanitization, reserved-name skip, deterministic dedup), NewStaticHeaderProvider, resourceAttributesToStringMap, and emitter-level tests asserting ce_<sanitized> extensions land on published/batched events
• Manual verification against a live chip-ingress endpoint (not done in this session)

[github-actions]

⚠️ API Diff Results - github.com/smartcontractkit/chainlink-common/pkg/chipingress

⚠️ Breaking Changes (1)

./ (1)

• NewEvent — Type changed:

func(
  string, 
  string, 
  []byte, 
  map[string]any, 
  + ...EventOpt
)
(CloudEvent, error)

✅ Compatible Changes (6)

./ (6)

• EventOpt — ➕ Added

• NewStaticHeaderProvider — ➕ Added

• SanitizeExtensionName — ➕ Added

• SanitizeMetadataHeaders — ➕ Added

• SanitizeMetadataValue — ➕ Added

• WithResourceAttributeExtensions — ➕ Added

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