Consolidate Day and Week event editing behavior

[Uarmagan]

What to build

Investigate and decide whether Day and Week event editing should share one editor behavior contract.

Right now both views use the event form, but they host it through different layers. Day opens the form through the floating editor and writes changes back to the active draft. Week opens the same form through its Week draft/edit layer, which also handles movement, resizing, recurring-event save choices, and the multi-column grid.

The first goal is to understand why these layers differ and whether they need to. From the user's point of view, editing an event in Day and Week should be almost one-to-one the same, except that Week shows multiple day columns while Day shows one day.

This is not a request to blindly remove Week-specific behavior. The decision to make is how much of Week's drag/edit layer should stay view-specific, and how much common editing behavior should move to a shared editor contract used by both Day and Week.

Acceptance criteria

• Document the current Day and Week event editing paths, including where event updates, save, delete, duplicate, and recurrence changes flow.
• Identify every meaningful behavior difference between Day and Week editing, and decide whether each one is intentional or accidental.
• Decide which editor behaviors should be shared and which Week-specific draft behaviors should stay separate.
• If consolidation is appropriate, define the smallest shared editor contract that can support both views.
• Common event form actions behave the same in Day and Week: title, description, priority, date/time, recurrence, save, delete, and duplicate.
• Week-specific drag, resize, keyboard movement, and multi-column placement behavior still works.
• Recurring-event save/delete prompts still appear only when appropriate.
• Browser verification covers editing a timed event and toggling Repeat in both Day and Week.

Blocked by

None - can start immediately

[tyler-dane]

Removed refactor label, because we have a refactor type for this (see right section)