feat: add whitelist support and configurable in-game command access mode

[FaiThiX]

Adds flexible access control for in-game bot commands by introducing a whitelist
alongside the existing blacklist approach, plus a selectable access mode.

What changed:

• Added new slash command /whitelist with subcommands:
  • add steamid
  • remove steamid
  • show
• Added new slash command /ingameaccess with subcommands:
  • mode (blacklist | whitelist)
  • show
• Added generalSettings.inGameCommandAccessMode with default blacklist.
• Extended instance schema with whitelist.steamIds and migration handling for existing instances.
• Updated in-game team message command gating:
  • blacklist mode: everyone allowed except blacklisted steam IDs.
  • whitelist mode: only whitelisted steam IDs allowed.
• Added new EN localization keys for whitelist/access mode texts and logs.
• Updated docs (commands.md, full_list_features.md) to include new commands and behavior.

Compatibility:

• Backward compatible for existing installations.
• Default behavior remains blacklist-based unless mode is explicitly changed.

Validation:

• Syntax checks passed for changed JS files (node --check).
• Type-check/tests passed via npm test -- --pretty false (tsc --noEmit).
• Tested in-game command behavior for all obvious scenarios.