Address feedback from @yinwm for long-running daemon use:
- Replace sync.Map with a fixed-size sharded lock array (64 mutexes).
Keys are mapped via FNV hash, so memory is O(1) regardless of how
many sessions are created over the process lifetime.
- Increase scanner buffer cap from 1 MB to 10 MB. Tool results
(read_file on large files, web search responses) can easily exceed
1 MB. The scanner still starts at 64 KB and only grows as needed.
d55e5540af