v1.1.0 — Smarter symlink handling

Replaces blanket symlink rejection with path containment:

• Symlinks are now followed and the resolved path is checked against allowed roots (workspace, /tmp)
• Symlinks within the workspace or /tmp work normally
• Symlinks pointing outside (e.g. ln -s ~/.ssh/id_rsa secrets.pdf) are blocked
• File extension validated on the resolved (real) file, not just the link name