[Bug] Desktop TUI: "Files changed" (last round) panel always empty on Windows, file/patch parts never persisted

Environment

• OpenCode Desktop 1.18.18 (reproduced on 1.16.2 too)
• Windows 11
• Workspace root C:\LiteWorkSpace is NOT a git repo (git repos live in subdirectories)

Symptom
The right-side panel has two sections: "Changes this round" and "Git changes". The Git section always renders correctly, but "Changes this round" has been empty forever, even after edit/write tools successfully modified files in the session.

Evidence
Querying opencode db (part table) shows:

• tool parts are persisted normally (4622 rows, edit tool parts include filePath in input)
• file parts: only 1 row ever (old session)
• patch parts: only 7 rows, all from June 2026 in a different workspace
• Recent edit calls (after upgrading to 1.18.18) still produce zero file/patch parts

Suspicion
Likely related to #41399 (session file tracking for the same panel): the workspace root not being a git repo may break the file/patch persistence path. Most users run OpenCode inside a git repo root, which would explain why this is not widely reported