Symlink path traversal allows arbitrary file access + extra_flags injection from untrusted profiles

[consigcody94]

Found via code audit.

1. Symlink path traversal (HIGH) - internal/claude/plugin.go:91-133: Profile path field not validated. os.Symlink creates links to arbitrary files.

2. extra_flags injection (HIGH) - internal/claude/flags.go:58-59: Profile YAML can inject --dangerously-skip-permissions or override flags.

3. Signal handler race (HIGH) - internal/claude/cleanup.go:59-68: SIGTERM sent without waiting for process exit before directory cleanup.