ChatChannels

### Changelog

- **FTB Ranks permission fix**
  - Fixed integration with FTB Ranks so that boolean permission values are read correctly from `PermissionValue` (using `asBooleanOrFalse()`).
  - Permission nodes like `chat.channels.global`, `chat.channels.local`, `chat.channels.trade` and `chat.channels.staff` now work as expected when defined in `ranks.snbt`.

- **Per‑channel message display**
  - Chat messages are now displayed **only in their own channel**:
    - Messages sent to `global` are only visible while you are in the `global` channel.
    - Messages sent to `local`, `trade`, `staff`, etc. are only visible inside the corresponding channel.
  - The client keeps a **separate message history per channel** and fully redraws the chat when you switch channels, so each channel shows only its own messages.
  - Channels are still highlighted when new messages arrive in a non‑active channel.

- **Private messages / PM channel**
  - Private messages are now sent through a dedicated **`pm`** channel (`ChannelType.PRIVATE`).
  - Private messages are visible **only in the `pm` channel** and do not appear in other channels.
  - When a new private message arrives, the client automatically switches to the `pm` channel and shows the PM history.

- **Command changes**
  - The mod’s private message command has been renamed from **`/msg`** to **`/pm`** to avoid conflicts with vanilla `/msg`.
  - Use:
    - `/pm <player> <message>` – send a private message using the ChatChannels PM system.