feat: Reduce Memory Overhead - Efficient Initialization Techniques

[Mavis2103]

I suggest implementing a memory limit feature or an alternative method to avoid loading full content into RAM. My machine has 16GB of RAM, but it consistently crashes due to memory exhaustion when running large projects. Is there a way to optimize this behavior or stream data instead of storing it all in memory?

[justrach]

Addressed in v0.2.54:

• mmap-backed trigram index — ~0 RSS for the trigram index (PR perf: mmap-backed trigram index for instant startup and lower RSS #167)
• mmap_overlay pattern — incremental updates without heap rebuild (PR perf: mmap overlay pattern for zero-heap incremental updates #190)
• clearAndFree in releaseContents — fully releases HashMap memory (PR fix: releaseContents reclaims HashMap bucket memory (#187) #189)
• Content release for repos >1000 files — frees file content after indexing
• Home directory blocking — prevents accidental full-home indexing (PR fix: block home directory indexing to prevent 17GB RAM spike (#174) #178)

Peak RSS reduced by ~121MB on 5k-file repos. The trigram index data now lives in OS page cache, not heap.