Crash Link

Crash Link - 1.21.1 V 4.1.0

This update focuses on maintenance, stability, and better server support tools.

Changes:
- Cleaned up the internal Java package namespace from the old template-style package to `net.setokaiba218.crashlink`.
- Kept the public mod id as `crashlink`, so existing configs, mod identity, and normal user-facing behaviour remain stable.
- Added `/crashlinkserver doctor`, a new server diagnostic command for staff and server owners.
- The Doctor command checks important Crash Link server paths and setup state, including:
  - Config folder
  - Config write access
  - Server config file
  - Session tracker file
  - Logs folder
  - Crash reports folder
  - Support packet folder
  - Latest log detection
  - Latest crash report detection
  - Permission status
- Improved mclo.gs upload failure messages.
- Upload failures should now give clearer reasons instead of one vague error.
- Better upload errors can now point players/staff toward:
  - Missing files
  - Empty files
  - Unreadable files
  - mclo.gs timeouts
  - Connection/DNS problems
  - Rejected uploads
  - Invalid mclo.gs responses

Notes:
- `/crashlinkserver doctor` is mainly intended for dedicated servers and staff troubleshooting.
- The package cleanup is internal and should not change normal player usage.
- Existing configs and the public mod id remain unchanged.
- This update has been tested with build, client launch, server launch, and server command checks.