refactor(network): finalize forwarding removal and compress script

[LucaLin233]

Summary

• Remove the completed forwarding/RA migration warning, read-only status rows, compatibility runtime capture, documentation, and migration-only tests.
• Merge consecutive local declarations without changing initialization order or typed-array declarations.
• Table-drive managed-file backup metadata and restore scope resolution while preserving paths, formats, ordering, and rollback behavior.
• Share PID tracking, dependency checks, RTT output, and health-delta calculations.

Size

modules/network-optimize.sh: 3522 -> 3252 lines (-270). This starts the mechanical compression phase while keeping the remaining 3000-3100 target for a later isolated pass.

Validation

• bash -n modules/network-optimize.sh
• shellcheck --severity=warning modules/network-optimize.sh
• shellcheck -x --severity=error linux_setup.sh modules/*.sh tools/*.sh tests/*.sh
• bash tests/test-network-optimize.sh
• bash tests/test-network-optimize-entry.sh
• bash tests/test-network-optimize-verify.sh
• bash tests/run.sh
• no forwarding, RA, ip_forward, or accept_ra references remain in the network module, its tests, or README

Compatibility

CLI behavior, state paths and formats, initcwnd route handling, BBR/fq/buffer calculations, and restore previous/initial semantics remain unchanged. Existing historical backup files are not deleted or rewritten by this refactor.