test: 별칭 전용 테스트 삭제 + 영향 테스트/fixture 갱신

kebab-search/tests/lexical.rs 의 alias 채널 테스트 + insert_chunk_with_aliases
헬퍼 제거(body 회수 회귀 테스트로 대체). Chunk 리터럴 aliases: None 제거
(embedding_records_fk/idempotency/inspect). chunk 스냅샷 fixture 의 aliases
키 제거. config_migrate 는 ingest.code 앵커로, corpus_revision/search_lexical
주석은 V013 비-bump 명시로 갱신.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/kebab-app/tests/search_lexical.rs

@@ -111,7 +111,8 @@ fn first_ingest_bumps_corpus_revision() {
     store_before.run_migrations().unwrap();
     // V004 seeds 0; V009 + V010 + V011 migrations each bump by 1 to
     // invalidate stale LRU caches (spec §5.2). Baseline before ingest = 3.
-    // (V012 derivation_cache is purely additive — does NOT bump.)
+    // (V012 derivation_cache + V013 drop-chunk-aliases are structural/additive
+    // — neither bumps corpus_revision.)
     let baseline = store_before.corpus_revision();
     assert_eq!(baseline, 3, "fresh store post-V011 baseline = 3");