📝 docs: sync README / HANDOFF / CLAUDE / skill / design for fb-27

- README 명령 표 에 `kebab schema` 추가
- HANDOFF post-도그푸딩 항목 한 줄
- CLAUDE.md wire schema 절 schema.v1 / error.v1 추가
- integrations skill — schema 활용 안내 (additive)
- design §10.1 capability matrix subsection 신설

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

integrations/claude-code/kebab/SKILL.md

@@ -57,6 +57,16 @@ kebab ask "<question>" --json
 - `ask --json`'s `citations[]` mirrors `search_hit.v1` minus retrieval internals — same `doc_path` / `citation` shape.
 - Schema reference lives in the kebab repo at `docs/wire-schema/v1/*.schema.json` if a field is unclear.
 
+## Capability discovery
+
+Before using streaming or multi-turn features, you can probe what this binary supports:
+
+```bash
+kebab schema --json
+```
+
+Returns a `schema.v1` object with: `wire.schemas` (supported wire ids), `capabilities` (bool flags — e.g. `multi_turn`, `streaming_ingest`), `models` (version cascade 6-axis), and `stats` (doc/chunk/asset count + last_ingest_at). Gate streaming / session flows on `capabilities.streaming_ingest` / `capabilities.multi_turn` being `true`. This call is cheap (no LLM) and can be run once per session.
+
 ## Quick health check
 
 If a call fails or returns suspicious output, run `kebab doctor` first — it surfaces config-load / data-dir / Ollama-reachability problems in one line each. Don't silently retry on errors; report the doctor output.