Plan V2 planner and time-blocking surfaces

[solankydev]

Goal

Track the deferred V2 planning work without mixing it into GTD V1 release scope.

Acceptance criteria

• Define how planned dates, deadlines, and future time blocks should interact.
• Decide which planner views are V2 and which remain out of V1.
• Keep the current data model compatible with future time-blocking work.
• Avoid adding calendar/planner UI until the GTD V1 task workflow is proven.

Privacy note

This issue stays product-level and does not mention private calendars, task names, or personal routines.

[github-actions]

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