### Added
- Added Runtime-backed durable bloc prompt-cache control-plane routes under `/api/gateway/blocs/*`, including KV manifest/list/ensure/load/delete/prune helpers for exact-reuse workflows.
- Added Gateway-owned workspace file helper support plus focused route and contract coverage for durable blocs, model residency, notifier behavior, and Runtime-backed capability discovery.

### Changed
- Raised the Runtime floor to `AbstractRuntime[multimodal,mcp-worker]>=0.4.19` and moved Gateway's public provider/media/tool boundary behind Runtime facades rather than direct package imports.
- Updated Apple/GPU install profiles to cascade through Runtime's aggregate extras and excluded internal `tests/`, `flows/`, and backlog notes from source distributions.
- Expanded the docs and capability contract to cover durable blocs, media/model residency, Runtime-backed email/Telegram helpers, and the current Docker/runtime dependency shape.

### Fixed
- Gateway no longer reads AbstractCore config for LLM helper defaults; provider/model resolution now follows request values, Gateway env, and flow defaults with a clear config error when unset.
- Gateway's operator email, Telegram, and notification paths now use Runtime's AbstractCore host facades, while local file/workspace helpers stay owned by Gateway.
- Capability discovery and prompt-cache readiness reporting now better reflect the actual state of generated-media, voice/audio, and provider-backed cache controls.
