fix(p10-1a-2): PR review round 1 — doc inconsistencies + observable backfill error path

PR #140 회차 1 actionable 7건 반영:
- docs/SMOKE.md: parser_version "code-rust-ast-v1" → "code-rust-v1" (chunker_version 과 혼동); jq path .citation.code_lang → .citation.lang (wire 의 code_lang 은 SearchHit top-level)
- docs/ARCHITECTURE.md: Mermaid pcode→ptypes 잘못된 edge → pcode→core 로 정정 (kebab-parse-code Cargo.toml 실제 dep 와 일치); 디렉토리 트리에서 code-rust-ast-v1 chunker 표기 위치 kebab-parse-code → kebab-chunk 로 정정
- crates/kebab-app/src/app.rs: backfill_repo 의 .ok().flatten() 실패 silent swallow → tracing::warn 로 관측 가능, 비-abort 의도 보존
- crates/kebab-parse-code/src/rust.rs: impl_item arm 의 "function_item 만 unit 생성" 1A scope 한정 주석을 외부에서도 보이도록 arm 상단에 한 줄 추가 (내부 주석은 유지)

verify: kebab-parse-code 7/7 / kebab-app --lib 51/51 / code_ingest_smoke 3/3 green; touched-crate clippy clean (재부팅 전 검증).

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

crates/kebab-app/src/app.rs

@@ -822,11 +822,22 @@ impl App {
             let repo_val = cache
                 .entry(hit.doc_id.clone())
                 .or_insert_with(|| {
-                    self.sqlite
-                        .get_document(&hit.doc_id)
-                        .ok()
-                        .flatten()
-                        .and_then(|doc| doc.metadata.repo)
+                    // Deliberately non-aborting: a failed store lookup for
+                    // one hit must not abort the whole search response. Log
+                    // the error so it's observable rather than silently
+                    // dropped (review #140 round 1).
+                    match self.sqlite.get_document(&hit.doc_id) {
+                        Ok(opt) => opt.and_then(|doc| doc.metadata.repo),
+                        Err(e) => {
+                            tracing::warn!(
+                                target: "kebab-app",
+                                doc_id = %hit.doc_id,
+                                error = %e,
+                                "backfill_repo: get_document failed; leaving hit.repo = None"
+                            );
+                            None
+                        }
+                    }
                 });
             if let Some(r) = repo_val {
                 hit.repo = Some(r.clone());