feat(schema): add active_parsers + active_chunkers arrays to schema.v1.models (Bug #13)

이전: schema.v1.models 가 parser_version / chunker_version 단일 값만 보고 →
multi-medium corpus (md + pdf + code Rust/Python + dockerfile + k8s + manifest)
의 version cascade audit 누락 risk.

이후: additive minor — Models struct 에 active_parsers + active_chunkers Vec<String>
추가. backward compat: 기존 단일 field 보존 (markdown default), 신규 array 는
optional (#[serde(default)] + JSON schema required 미포함).

source:
- kebab_store_sqlite::fetch_distinct_parser_versions() 가
  documents.parser_version DISTINCT + ORDER BY 반환.
- fetch_distinct_chunker_versions() 가 chunks.chunker_version 동일 pattern.
- collect_models 가 매 schema 호출마다 재계산 (cache 없음 — R-3 자동 해결).

wire schema additive only — 메이저 bump 불필요. v0.20.1 minor 로 충분.
integrations/claude-code/kebab/SKILL.md 동기 갱신.

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

integrations/claude-code/kebab/SKILL.md

@@ -152,7 +152,7 @@ Claude Code spawns `kebab mcp` at session start; the process stays alive across
 
 Before using streaming or multi-turn features, probe what this binary supports — call `mcp__kebab__schema` (or CLI `kebab schema --json`):
 
-Returns `schema.v1`: `wire.schemas` (supported wire ids), `capabilities` (bool flags — e.g. `streaming_ask`, `rag_multi_turn`), `models` (version cascade 6-axis), `stats` (doc/chunk/asset count + last_ingest_at, plus p9-fb-37 health surface: `media_breakdown` per-kind doc counts (5 zero-padded keys: markdown / pdf / image / audio / other), `lang_breakdown` per BCP-47 lang (NULL keyed as the literal string `"null"`), `index_bytes.{sqlite,lancedb}` on-disk byte sums, `stale_doc_count` for docs older than `config.search.stale_threshold_days`). Gate streaming / session flows on `capabilities.streaming_ask` / `capabilities.rag_multi_turn` being `true`. Cheap call (no LLM), once per session.
+Returns `schema.v1`: `wire.schemas` (supported wire ids), `capabilities` (bool flags — e.g. `streaming_ask`, `rag_multi_turn`), `models` (version cascade 6-axis + v0.20.1 `active_parsers` / `active_chunkers` arrays for multi-version corpora), `stats` (doc/chunk/asset count + last_ingest_at, plus p9-fb-37 health surface: `media_breakdown` per-kind doc counts (5 zero-padded keys: markdown / pdf / image / audio / other), `lang_breakdown` per BCP-47 lang (NULL keyed as the literal string `"null"`), `index_bytes.{sqlite,lancedb}` on-disk byte sums, `stale_doc_count` for docs older than `config.search.stale_threshold_days`). Gate streaming / session flows on `capabilities.streaming_ask` / `capabilities.rag_multi_turn` being `true`. Cheap call (no LLM), once per session.
 
 ## Quick health check