perf(output): close byte gaps vs RTK on env, deps, ls, git diff

env_cmd: drop LS_COLORS + 15 noise vars + 14 prefix patterns,
  truncate PATH to 5 entries, cap long values at 200 chars.
  3346 B → 1190 B (-64%), now within 20% of RTK's 994 B.

deps: truncate dependency lists after 10 items with '+N more'.
  399 B → 229 B (-43%), now BEATS RTK's 257 B.

ls: remove footer line ('N files, M dirs').
  315 B → 296 B, now within 3% of RTK's 287 B.

git diff: strip context lines, keep only stat + file headers + +/- lines
  with per-file addition/deletion counts. Matches RTK's compact format.