feat(tools): three new native file tools — batch_read, glob, file_info

batch_read — read multiple files in one call with parallel goroutines.
  Replaces N serial read_file calls with a single parallel batch.
  Addresses the fast_read benchmark bottleneck (23%, 163s across 10 iter).

glob — file finding by glob pattern. Uses filepath.Glob for simple
  patterns (zero-walk) and filepath.Walk for recursive patterns.
  Returns {path, size, is_dir} sorted by mtime.

file_info — file metadata without forking stat/ls. Returns size,
  mod_time (ISO8601), mode string, is_dir, is_symlink, is_regular.

Security: all three use the same danger.ClassifyPath + CheckOperation
  gating, O_NOFOLLOW on file opens, and classifyToolCall entries for
  the batch approval gate. Zero new dependencies. 14 new tests.

Author: molty3000