Preview and confirm repeated sensor values before writing

[BelhsanHmida]

Add a confirmation step that shows the concrete values generated from a recording session before they are persisted. The preview must make DST effects and belief collisions visible to the user.

Acceptance criteria

• Let the user choose no repetition, daily repetition, or repetition on the same weekday.
• For repeated values, require a repeat-until date.
• Let the user set the belief time, defaulting to the current time.
• Optionally accept a rolling belief horizon if it is included in the initial scope.
• Expand the recording before persistence and show all event starts that will be written.
• Warn without blocking when spring-forward values will be omitted.
• Warn without blocking when fall-back values will be written to both repeated hours.
• Show exact collisions and explain that existing beliefs will win.
• Show counts for values to create, duplicate across a DST overlap, omit, and skip.
• Write values only after explicit confirmation.
• Keep the recording editable when the user returns from the preview.

Tests

• Preview without repetition.
• Daily and same-weekday previews.
• Spring-forward and fall-back warning text and counts.
• Collision preview and final persistence summary.
• Cancel or return-to-edit without writing data.

Out of scope

• Alternative DST policies in the initial UI.
• Schema-level recurring beliefs.