Add egress boundary gates to segmentation skill

[cuph7022]

Summary

• Add an egress boundary and internet exit review step to the network segmentation skill.
• Add SEG-EGRESS finding IDs for unrestricted outbound access, proxy/DNS bypass, port-only allowlists, stale exceptions, alternate egress paths, and missing destination/logging evidence.
• Extend testing guidance and the output format with an egress boundary matrix.
• Bump the segmentation skill version to 1.1.0.

Closes #1685

Validation

• Reviewed the GitHub diff for the single Markdown file change.
• Confirmed the updated skill includes version: "1.1.0" and SEG-EGRESS-01 through SEG-EGRESS-07.
• Did not clone, install dependencies, or run project code.