v0.6.6

Fixed

• OOM during indexing of large codebases (Vec/HashMap over-allocation): After each doubling growth, Rust's Vec and FxHashMap may carry up to 2× excess capacity. On a 62 000-file corpus this contributes tens to hundreds of MB of wasted heap. Three changes address this:
  1. SearchEngine::compact_memory() — a new method that calls shrink_to_fit() on symbol_cache (both outer Vec and every inner Vec<Symbol>), pending_imports, and the trigram HashMap. Called automatically every 50 batches during the initial index build, so memory is reclaimed without waiting for finalize().
  2. SearchEngine::finalize() — additionally shrinks file_metadata and runs a full compact_memory() pass once indexing completes.
  3. TrigramIndex::finalize() — now includes shrink_to_fit() on the FxHashMap<Trigram, RoaringBitmap> which can hold ~50% empty bucket slots after bulk insertion.