feat(cli): drop redundant 'wormhole send/receive' lines from --help

[mvanhorn]

The default binary name is wormhole-rs, but the --help after-help text references wormhole send and wormhole receive:

Run a subcommand with `--help` to know how it's used.
To send files, use `wormhole send <PATH>`.
To receive files, use `wormhole receive <CODE>`.

So the example commands don't match what users actually type. Per @felinira's comment on #209, the cleanest fix is to drop the last two lines - the per-subcommand wormhole-rs send --help / receive --help already documents what those subcommands need.

Changes:

• cli/src/main.rs:253-255: keep only Run a subcommand with --help to know how it's used. in after_help.
• cli/tests/cmd/help.stdout and cli/tests/cmd/basic.stderr: drop the two corresponding lines from the trycmd snapshots.

Verified locally:

$ cargo test --test cli_tests
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

All 9 trycmd cases pass.

Closes #209.

This contribution was developed with AI assistance (Claude Code).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.39%. Comparing base (8b571ba) to head (7b7aebf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #355      +/-   ##
==========================================
+ Coverage   39.36%   39.39%   +0.03%     
==========================================
  Files          20       20              
  Lines        3292     3292              
==========================================
+ Hits         1296     1297       +1     
+ Misses       1996     1995       -1     

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