Document all conditions that trigger file lock and unlock

[tbsbdr]

Create clear documentation outlining all conditions under which a file becomes locked or unlocked.

This should include:

• User actions (e.g. opening, editing, saving)
• System events (e.g. timeouts, crashes, background processes)
• Temporary or system files (e.g. ~$ files)
• etc. ...

The goal is to make file locking behavior transparent to users so they understand why a file is locked and when it will be released.

@Svanvith as discussed 🙏

[Svanvith]

#800