Restructure: Move final 12 root files into packages (klausur-service)

ocr/spell/  (3): smart_spell, core, text
upload/     (3): api, chunked, mobile
crawler/    (3): github, github_core, github_parsers
+ unified_grid → grid/, tesseract_extractor → ocr/engines/, htr_api → ocr/pipeline/

12 shims added. Only main.py, config.py, storage + RAG files remain at root.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

klausur-service/backend/crawler/github.py

@@ -0,0 +1,35 @@
+"""
+GitHub Repository Crawler — Barrel Re-export
+
+Split into:
+- github_crawler_parsers.py  — ExtractedDocument, MarkdownParser, HTMLParser, JSONParser
+- github_crawler_core.py     — GitHubCrawler, RepositoryDownloader, crawl_source
+
+All public names are re-exported here for backward compatibility.
+"""
+
+# Parsers
+from .github_parsers import (  # noqa: F401
+    ExtractedDocument,
+    MarkdownParser,
+    HTMLParser,
+    JSONParser,
+)
+
+# Crawler and downloader
+from .github_core import (  # noqa: F401
+    GITHUB_API_URL,
+    GITLAB_API_URL,
+    GITHUB_TOKEN,
+    MAX_FILE_SIZE,
+    REQUEST_TIMEOUT,
+    RATE_LIMIT_DELAY,
+    GitHubCrawler,
+    RepositoryDownloader,
+    crawl_source,
+    main,
+)
+
+if __name__ == "__main__":
+    import asyncio
+    asyncio.run(main())