Fix roster synchronization and empty-row handling

[ciolansteen]

Summary

• request .playerbots bot list after logging in bots and import its system-message roster into the local tracker
• normalize class names against the addon's existing class definitions, reuse empty class slots, and avoid duplicate tracked names
• coalesce repeated roster scheduling so only the latest delayed request runs
• allow stale unnamed SavedVariables rows to be deleted and prevent empty slots from opening character panels
• make the main window raise when clicked, and remove the isolated UTF-8 BOM from PBM_ClassTabs.lua

Problem

The addon stores its roster locally and .playerbots bot add * does not populate that SavedVariables roster. Existing bots can therefore be online while the manager remains empty. In addition, unnamed rows containing stale class/spec data cannot be deleted because the delete handler returns early when name == "".

The login/logout buttons also used PARTY, which the client rejects when the player is not grouped.

Testing

• parsed representative online/offline roster output with Lua 5.1, including Death Knight normalization, duplicate suppression, color codes, unrelated messages, and invalid classes
• verified queued C_Timer callbacks and the WotLK OnUpdate fallback both implement last-schedule-wins behavior
• luac5.1 -p passed for all 53 Lua files
• verified no UTF-8 BOM remains in Lua files
• git diff --check

Roster synchronization has not yet been manually validated end-to-end in the WoW client against every server configuration.