Add durable inbound event bridge for managed chat runtimes

[chubes4]

Problem

An always-available WordPress agent needs WordPress to acknowledge and durably queue signed chat webhooks while its coding runtime may be offline. wp-coding-agents currently owns outbound CLI channel registration and Kimaki runtime setup, but has no provider-neutral inbound event contract.

Contract

• Generate a WordPress ingress/queue component with signed-adapter extension points.
• Deduplicate, lease, acknowledge, and retry normalized events durably.
• Return webhook acknowledgements before runtime provisioning.
• Emit a generic runtime-requested hook; know nothing about hosting providers, SecEx, WP Cloud, A8C, Automattic, or product agents.
• Provide an argv-safe runtime connector that delivers claimed events through stock Kimaki behavior.
• Keep signatures, authorization headers, and reusable credentials out of queue records and diagnostics.

AI assistance

GPT-5.6 Sol in OpenCode was used to inspect the current bridge and external-runtime contracts and draft this issue. Chris Huber is directing and reviewing the work.

[chubes4]

PR #383 merged the durable ingress queue before the external runtime connector and runtime-scoped claim commits landed on its branch. Reopening this tracker until the follow-up connector diff is merged.

AI assistance: OpenAI gpt-5.6-sol via OpenCode verified the merged and branch refs and identified the unpublished commits. Chris Huber reviewed and remains responsible for the follow-up.