feat(ocr): unify config, add manga translation pipeline and context lookahead

- Consolidate module configs into root config.example.json with ocr, vision, and epub sections

- Split LLM OCR workflows into novel_ocr.py (prose) and manga_ocr_llm.py (manga)

- Remove gemini_direct_ocr.py in favor of OpenAI-compatible API endpoints

- Support direct manga translation via --translate, --target-lang, and glossary.md

- Add bidirectional context support: past translations (--context-pages) and lookahead Japanese text (--context-pages-ahead)

- Add per-page JSON audit logging under logs/ and expose OpenAI sampling parameters

ocr/__init__.py

@@ -1,15 +1,28 @@
 """
-OCR module: batch-transcribes scanned light novel pages (vertical Japanese
-text) into per-page .txt files, ready for the epub_builder module.
+OCR module: batch-transcribes (or translates) scanned pages into per-page
+.txt files. Light novel and manga pages are handled by separate scripts,
+since their layouts need genuinely different logic (dense running prose
+vs. scattered, typed speech bubbles that benefit from translation +
+glossary + cross-page continuity context).
 
-Several interchangeable backends are provided as standalone scripts:
+Novel (light novel, dense running prose):
+- novel_ocr.py          Any OpenAI-compatible API (OpenRouter, a direct
+                          provider endpoint, a self-hosted proxy, etc.)
+                          with a multimodal model. Recommended.
+- google_vision_ocr.py  Classic OCR via Google Cloud Vision (no LLM,
+                          --mode novel).
 
-- openrouter_ocr.py    Recommended. Any OpenAI-compatible API (OpenRouter,
-                        a self-hosted proxy, etc.) with a multimodal model.
-- gemini_direct_ocr.py Same idea, but calling the Gemini API directly.
-- google_vision_ocr.py Classic OCR via Google Cloud Vision (no LLM).
-- local_mangaocr_ocr.py Fully offline, no cloud account, via manga-ocr.
+Manga (speech bubbles / narration boxes / SFX):
+- manga_ocr_llm.py      Any OpenAI-compatible API. Transcribe or
+                          --translate, with --glossary and --context-pages
+                          for cross-page continuity. Recommended.
+- google_vision_ocr.py  Classic OCR via Google Cloud Vision (no LLM,
+                          --mode manga; transcription only, no translation).
+- local_mangaocr_ocr.py Fully offline, no cloud account, via manga-ocr
+                          (also supports --mode novel via column
+                          segmentation, transcription only).
 
 Each script is self-contained and runnable directly, e.g.:
-    python -m ocr.openrouter_ocr --input ./pages --output ./out
+    python -m ocr.novel_ocr --input ./pages --output ./out
+    python -m ocr.manga_ocr_llm --input ./pages --output ./out --translate
 """