Task List: Fix subtask status dot refresh and preserve card classes

[christenbc]

Summary

• Update status-dot click handling to immediately refresh subtask card visuals (dot, checkbox, classes, and CSS vars).
• Reuse the shared status handler for newly-created status dots to keep behavior consistent.
• Preserve existing task-card modifier classes while toggling status/priority/completion.

Test Plan

• Toggle status from a subtask dot; UI updates immediately.
• Toggle status from a parent task dot; UI updates immediately.
• Verify status-dot icon/color and checkbox state match new status.
• Smoke-check task list rendering after reload.

[callumalpass]

Thank you very much @christenbc--this is a nice contribution. Merging for the next release.