feat(odata-v4): Add nested $expand, $batch, $search, and ETags

- Implement nested $expand with depth limiting (e.g., $expand=owner($expand=department))
- Remove @expanded suffix, use OData standard property names
- Add $batch endpoint for bulk operations (read and write changesets)
- Implement $search parameter for full-text search
- Add ETag generation and optimistic concurrency control
- Support If-Match and If-None-Match headers
- Return 412 Precondition Failed on ETag mismatch
- Support weak ETags (W/"...")
- Add depth limit configuration (maxExpandDepth)
- Improve expand parameter parsing to handle complex nested syntax

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot