Support rewrite_manifests table maintenance

Feature Request / Improvement

Rewriting manifests without changing data speeds up scan planning when a table has accumulated many small manifests. Java exposes this as Table.rewriteManifests() (Spark: rewrite_manifests).

Scope: an explicit maintenance operation that reads the current snapshot's manifests, regroups entries, rewrites them preserving sequence numbers (entries rewritten as EXISTING) and, for V3, first_row_id, and commits a replace snapshot. Related: #270 tracks automatic manifest merging on write; this covers the explicit maintenance API.

找出與 Table.rewriteManifests() 對應的 Python 資料表維護/API 入口點；先閱讀目前的快照與資訊清單管理路徑。完成的標準是：有一個明確的操作重新分組目前的資訊清單、保留序號與 V3 first_row_id、將重寫後的項目标記為 EXISTING，並提交一個替換快照。