* feat(core): add runImage and native image model adapters
Applications that generate or edit images had to call image APIs outside the framework and rebuild the same reliability code each time: retries, fallback across providers, error classification, and a record of every call. runImage() does this once, on an ImageModelAdapter interface that core owns, so no third-party SDK sits between OMA and the provider response it has to classify.
runImage() tries an ordered chain of models, retries retryable failures with jittered backoff that honors Retry-After, moves to the next model on anything else, reads the output format and size from the bytes, runs an optional validate check, and reports every provider call through result.attempts and onAttempt. It resolves with status failed instead of throwing when the chain runs out.
OpenAIImageAdapter (OpenAI Images API and compatible endpoints) and SeedreamImageAdapter (Seedream on Volcengine Ark) call the HTTP APIs with fetch, classify safety rejections as content_policy, fail rather than drop input they cannot use, request base64 output only, and honor egressPolicy. ImageModelError carries the normalized type and retryable flag, and isRetryableError() returns that flag.
Refs #469
* fix(core): keep runImage independent of attempt sinks and caller signals
onAttempt is no longer awaited, so a stalled or rejecting sink cannot hold up retries, cancellation, or the result. A caller that aborts while validate is pending now gets its abort instead of a successful image. Each attempt removes its abort listener from the caller's signal when it ends, so a signal reused across many calls no longer accumulates listeners.
Systematic documentation review: 12 new docs pages (coordinator, streaming, budgets and limits, errors, hooks and callbacks, glossary, production checklist, Run Viewer, MCP, sandbox and shell, evaluation in CI, routing evaluation) plus a docs index; the three longest guides split with stub sections that keep existing anchors; observability release records moved to docs/internal; statements re-verified against the code and corrected; READMEs, AGENTS.md, CONTRIBUTING.md, and issue templates synced. Documentation only, no behavior change.
Jack Chen