fix: resolve {{ args.* }} placeholders in command run strings

Args placeholders in command `run` fields were never resolved before
execution, causing shlex.split to tokenize them into multiple tokens.
Now resolve_args() is called on each command's run string before
execution, matching the behavior already applied to the prompt body.

Closes #20

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs: update changelog for v0.2.0 release with fixes and improvements

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

release: v0.1.12 — new tagline

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

release: v0.1.11 — improved ralph new experience

- Launch claude with --dangerously-skip-permissions for uninterrupted setup
- Rewrite skill to accept plain-English descriptions instead of asking about internals
- Add user arguments knowledge to the skill

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>