chore: ignore docs/plans directory (#31)

Adds docs/plans/ to .gitignore and removes existing tracked files.
This directory is for temporary planning documents that should not
be version controlled.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: dreamiurg

.gitignore

@@ -98,5 +98,8 @@ temp/
 *.tmp
 .claude
 
+# Documentation drafts and plans
+docs/plans/
+
 # Git worktrees
 .worktrees/