Auto-scheduler moves a task but its pushed calendar block stays at the old time

[HomicideZero]

Describe the bug

When the auto-scheduler re-plans and moves a task that has already been pushed to Google Calendar (the "task block" feature), the task's calendar event is not updated — it stays at the old time. The in-app schedule shows the new time, but the Google Calendar event is stale, so the two disagree until something else dirties the block.

Root cause

The bulk re-plan path writes the task's new slot without marking the block for re-push:

• SchedulingService.scheduleTask updates scheduledStart/scheduledEnd but never sets blockDirty.
• repushDirtyBlocks only selects tasks that are blockDirty = true or scheduled-with-blockEventId = null (i.e. brand-new blocks). A task that was moved but already has a blockEventId matches neither, so its event is never updated.

Manual edits and drag-and-drop go through schedulePushTaskBlock and update correctly; only the bulk auto-schedule (scheduleAllTasksForUser) is affected.

Expected behavior

After an auto-schedule run, a moved task's Google Calendar event should move to the task's new time.

Fix

scheduleAllTasksForUser snapshots each task's pre-replan scheduledStart/scheduledEnd, and after scheduling flags blockDirty = true for tasks that have an existing blockEventId and actually moved. The existing repushDirtyBlocks → pushTaskBlock → updateExistingEvent path then moves the event in place. Unchanged slots are left untouched to avoid needless Calendar API churn.

Verified on a self-hosted instance: re-planning that shifts already-pushed tasks now updates the corresponding Google events in place (same event id, new time) instead of leaving them stale.