Anti-procrastination: detect repeatedly dragged tasks and offer actions

[gnacho]

Problem

Tasks whose due date keeps slipping are invisible: the due chip just changes color. Nothing helps the user decide what to do with a task they keep avoiding.

Definition

A task becomes a dragged task when its due date has been changed at least N times (default 3, configurable in Settings) without the task being completed in between. Dragged tasks get a distinct visual flag and, from the task modal, quick actions to unblock them.

Scope

In scope:

• Detection: count 'due' activity events (activity_events already stores {from, to} per change) since the last completion ('moved' to hecho) or creation.
• Visual flag: distinct indicator on the card and in the task modal (not the current due color, something unmistakable).
• Quick actions in the task modal: (1) reschedule deliberately via the existing NLP due input, (2) split into subtasks (existing subtask list), (3) mark as 'will do today' (sets due_date to today, resets the slip counter baseline).
• Threshold configurable in Settings (1-10, default 3); opt-out possible (0 = disabled).

Out of scope:

• Focus/pomodoro mode (separate feature, see the gamification track).
• Automatic rescheduling or any change without explicit user action.
• Nagging: no banners, no periodic reminders. The flag appears only on the affected task.

Technical notes

• Data source: activity_events (type 'due'), no schema change needed for detection; a settings key for the threshold.
• Similar statistics approach as the adaptive recurrence feature (real intervals from history).
• Server computes the slip count (cheap COUNT query); bootstrap/task detail expose it.
• i18n es/en required.

Acceptance criteria

• A task with 3 due changes and no completion is flagged; completing it clears the flag.
• Threshold change in Settings applies immediately.
• With the feature set to 0 nothing is flagged.
• Existing suite green + new server tests for the counter.