### Added
- Public AbstractCore Runtime facades for:
  - discovery/catalog snapshot queries (`get_abstractcore_discovery_facade(...)`)
  - prompt-cache and model-residency host control operations (`get_abstractcore_host_facade(...)`)
  - durable run-scoped child-run execution for image, TTS, STT, and direct LLM calls (`get_abstractcore_run_facade(...)`)
- `EffectType.MODEL_RESIDENCY` with AbstractCore-backed load/list/unload handling and VisualFlow lowering support for runtime-owned model residency control.

### Changed
- Minimum optional AbstractCore dependency floor is now `abstractcore>=2.13.20`.
- Local cached-vision discovery now depends on AbstractCore's public `get_local_vision_cache_catalog()` helper instead of private server internals.
- Local media residency no-op/unsupported responses now complete truthfully with warning/degraded metadata, and media-only results distinguish runtime orchestration identity from the actual media backend identity.
- Documentation was refreshed for the current Runtime/Core boundary, including root docs, ADR/backlog references, and AI-readable `llms.txt` / `llms-full.txt`.
