Fixed

• Folia: MSPT and TPS now come from the regions your players are in. Folia has no single server tick, and its MSPT and TPS methods answer for whichever region the calling thread belongs to. The plugin runs its checks on Folia's global region, which never carries players, so it saw a server that was always fast and the MSPT thresholds practically never fired. Distances on Folia were only steered by the chunk budget, the chunk generation safeguard and the memory safeguard. Now every online player's region is asked for its own MSPT and TPS every 5 seconds, on that region's thread, and the slowest region counts for the server. /vdt doctor shows where the figure comes from. Folia still offers no per tick timing, so the variance check stays off there. On Paper, Purpur and Spigot the MSPT reading is unchanged.
• /vdt doctor and the analyze and doctor lines of /vdt help printed raw key names (doctor.header, help.doctor, ...) instead of text since 2.13.0. A test now checks that every key in messages.yml is actually loaded.

Tested

• Folia 1.21.11 with 8 bots and a deliberately overloaded region: the plugin read the same MSPT as Folia's own /tps report and lowered the distances. AFK throttling and density scaling were checked in the same run.
• Paper 26.3: clean start, /vdt doctor, /vdt help and /vdt mspt correct.

No config changes.