The binary now derives command-line parsing from clap instead of maintaining a
custom parser. SEARCH_LIMIT remains an optional positional argument and keeps
its default of 1_000_000_000, while clap now owns usage errors, --help, and
--version output.
The parser stores the limit as NonZeroU64 so zero is rejected before the search
starts. The existing CLI parsing tests now exercise clap directly, and the
README documents the generated help/version flags plus the top-level program
structure.
Test Plan:
- cargo clippy
- cargo clippy --benches
- cargo clippy --tests
- cargo test
- cargo run -- --help
Trailer:
Refs: local request to replace custom argument parsing with clap
Dependencies: none
Add a concise README that documents how the program finds highly composite
numbers. The explanation covers the divisor-count formula, why exponent order
lets the search skip arbitrary numbers, and how the implementation generates
and filters record candidates.
Test Plan:
- Not run; documentation-only change.
Refs: N/A
ddidderr
