Restore the managed right chat after reload

[Minnona]

Summary

• persist the right-chat window ID in ElvCharacterDB when ElvUI identifies it
• reuse that saved ID when Blizzard restores the window outside the right panel
• use ChatFrame3 as a one-time legacy fallback for existing ElvUI layouts
• lock the managed right-chat window after restoring its anchor

Root cause

FindRightChatID only recognized the right chat by testing overlap with RightChatPanel. After a reload, Blizzard can restore the undocked window from stale saved coordinates before ElvUI positions its panels. The overlap check then returns no match, so ElvUI stops managing the window.

Impact

The configured right chat is restored to the right panel and locked during initialization, eliminating the manual unlock-and-snap workaround after reloads.

Validation

• Lua 5.1 syntax check passed
• tested in game using the fork branch
• right chat returned to the right panel after consecutive UI reloads
• restored chat remained locked and the per-character frame ID persisted