v0.1.5

Sorted key tables for namebases with prefix lookups, early-stop replay pruning,
pipelined parallel conversion with an ordered reorder buffer, and gigachess 0.1.10.

Added

• Namebase sorted key table (KeyTable). Replaced the $O(N)$ tree walk in
  Namebase::find_all with an in-memory flat sorted key table built on first lookup.
  For ~1M players, builds in < 300 ms and gives $O(\log N)$ binary search lookup
  (under 5 ms warm), completely resilient against damaged binary tree links in the file.
• Prefix lookup on namebases. Added Entities::find_players_prefix,
  find_tournaments_prefix, find_annotators_prefix, find_sources_prefix, and
  find_teams_prefix for fast prefix searches.
• Early-stop walk predicate (Flow). Added Flow::{Continue, SkipGame, Stop}
  and PositionQuery::early_stop_with, allowing per-game pruning during unindexed
  position search (e.g. via gigachess::reach::ReachSignature).
• Parallel conversion walk with ordered reorder buffer. Pipelined chunk decoding
  and delivery through a bounded reorder buffer, eliminating wave-barrier synchronization
  while preserving strict output order, deduplication, and recycling chunk allocations.
• Dependency bump: Upgraded gigachess to 0.1.10.

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Full Changelog: v0.1.4...v0.1.5