[Feature]: Personal Inbox & Quick-Capture Reminders

[espdesign]

Summary

Support lightweight personal task capture and ad-hoc reminders (via DM to the bot or /pm task inbox) decoupled from public Discord forum channels and project squad permission matrices.

Background & Context

ADR-0002 established mandatory project containers for Phase 1 to ensure relational integrity and clean forum thread routing. However, ADR-0002 explicitly noted:

"Re-evaluating standalone or personal inbox tasks remains open for consideration in future phases (e.g. alongside personal calendar sync in Phase 2)."
Contributors need a fast way to capture personal reminders and todos without cluttering public team project channels.

Proposed Capabilities

1. Personal Inbox Container:
   • Automatically maintain a user-scoped personal Inbox container with dedicated short ID numbering.
   • Tasks remain private to the user (visible only in personal lists, DMs, and user-scoped views).
2. DM Quick Capture:
   • Direct messages to the bot (or /pm task inbox title:... [due:...]) instantly capture tasks into the personal inbox.
3. Project Promotion / Triage:
   • Interactive button on the personal task card allows 1-click triage/promotion into any team Project container where the user holds squad membership.
4. Personal Reminder Alerts:
   • Due date reminders dispatched via DM per member notification preferences.

Acceptance Criteria

• Members can capture tasks in DMs without selecting a server channel or public project.
• Personal tasks do not create clutter or public threads in server channels.
• Members can move an inbox task into a team project container with sequential project ID assignment.
• Preserves relational invariants defined in ADR-0002 while providing seamless personal capture.