Web: one button to end a recurring operation or budget now

[corentin-core]

Context

Stopping a recurring planned operation or budget is possible today, but only by filling the "End date" field — which appears only once "Recurring" is ticked — or by using "Split from a date", folded inside a <details>. The common case is "this one is over now", and it deserves one button.

Proposed solution

• Add an "End" button on the target edit page for an existing recurring target, next to Delete.
• It sets the expiration to today and keeps every past occurrence, unlike Delete which erases the whole target.
• Confirm inline, the way Delete already does, stating that occurrences after today disappear from the forecast.
• The existing End date field stays for any other date.

Acceptance criteria

• An existing recurring target can be ended in one action from its edit page.
• Past occurrences and their links survive.
• No occurrence after today remains in the forecast.
• The button is absent on a non-recurring target and on one already expired.
• The ended target no longer shows under the default "Active only" filter.
• French translation added and the .mo recompiled.
• User docs updated.

Related issues

• Related to feat: edit specific iteration of recurring planned operation or budget #80