chore(ocr): T11/T12 — clippy clean + docs + v0.27.0 bump

T11: fix 12 clippy lints in paddle_onnx.rs/paddle_e2e.rs (doc overindent,
finish_non_exhaustive, map_or_else, RangeInclusive::contains, cast_lossless,
is_some_and, usize::from). Full-workspace clippy -D warnings = 0.

Smoke (paddle-onnx, real binary): clean_paragraph OCR verbatim-correct, real
per-region confidence (0.99/0.96/0.95), FTS5 lexical hit on Korean(검색)+
English(embedding), parser_version folds |ocr:1:paddle-onnx:<ver>. Big page
<4s inference (5.6s ingest incl. one-time session load).

T12: README [image.ocr].engine + ARCHITECTURE OCR row + SMOKE paddle-onnx config
+ HANDOFF + HOTFIXES dated entry. Workspace version 0.26.2 → 0.27.0 (minor:
new engine value + config keys). .gitattributes: onnx as plain blobs (no git-lfs).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/kebab-app/tests/common/mock_ocr.rs

@@ -39,6 +39,7 @@ impl OcrEngine for MockOcrEngine {
         "mock-v1".to_string()
     }
 
+    #[allow(clippy::unnecessary_literal_bound)]
     fn model(&self) -> &str {
         "mock-model"
     }