update-agent-context.sh breaks symlinks

[przadka]

Bug

update-agent-context.sh doesn't check if the target agent file (e.g., CLAUDE.md) is a symlink before writing to it. This converts the symlink into a regular file.

Steps to Reproduce

1. Create AGENTS.md with your agent instructions
2. Create symlink: ln -s AGENTS.md CLAUDE.md
3. Run /speckit.plan which calls update-agent-context.sh claude
4. Check CLAUDE.md - it's now a regular file instead of a symlink

Expected Behavior

The script should either:

• Detect symlinks and update the target file instead
• Skip updating symlinked files
• Warn the user that a symlink will be converted

Workaround

Manually restore the symlink after running the script:

rm CLAUDE.md && ln -s AGENTS.md CLAUDE.md