Add poisoned Linux depo repair script to tools/ + ./toolbox.sh easy entrypoint.

[sunmachine]

example-fix-depo-casing.mp4

#                    ████
#       ████████    ██████████     ▓▓▓▓
#     ████████████  ███████████   ▓▓▓▓▓▓
#    █████░░░█████░ █████░░░░░░░  ▓▓▓▓▓▓░
#    █████░  █████░ █████░         ▓▓▓▓░░
#    █████░  █████░ █████░          ░░░░
#    █████░  █████░ ██████████      █████
#    █████░  █████░ ██████████░     █████░
#     ░░░░░  █████░  ░░░░░░░░░░    ████░░░
#            █████░               ███░░░
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#      N E O T O K Y O ; R E B U I L D

Description

Follow-up to #2055 (and technically the OG investigation scripts). The launcher heal covers players automatically. This adds the manual tooling around it under tools/.

• check-depot-casing.sh run against a depot staging tree before every steamcmd upload. Exits 1 and lists any of the seven engine binaries staged under the wrong file name casing, so a bad upload gets caught before it ships.
• fix-linux-casing.sh user-run repair for an already broken Linux install. Same canonical list and newest-wins rules as the launcher heal, safe to run repeatedly.
• toolbox.sh single interactive entry point for the tools. Presents the tools as a numbered menu; a new tool joins with one line in its table.
• nt-logo.sh shared NT;RE logo banner, printed only when stdout is a terminal, so piped and CI output stays clean and exit codes are untouched.
• Points the sync comment in neo_case_heal.cpp at the renamed check script.

Testing on Linux

Against a real install with all seven binaries lowercased:

# Quick way, use toolbox.
./toolbox.sh


# Or run the scripts directly.
./check-depot-casing.sh <install root>   # 7 WRONG CASING lines, exit 1
./fix-linux-casing.sh <install root>     # 7 repairs

# Then re-run to verify...
./check-depot-casing.sh <install root>   # Depot casing OK. exit 0

Also drove both tools through toolbox.sh, and verified the logo stays silent when output is piped.