fix(imp): refresh search list after trash delete

[TDannhauer]

Summary

• Fix search-result delete so messages are moved to Trash (or leave the list) instead of sticking with an optimistic IMAP \Deleted mark when use_trash is enabled.
• Always refresh the search viewport after delete so synthetic BUIDs and rebuilt result sets stay in sync.
• If move-to-trash cannot run because the mailbox lacks expunge rights, fall back to mark-as-deleted instead of doing nothing.

Motivation

Deleting multiple messages from IMP search results painted them as deleted but left them in place, while the same action from a normal mailbox correctly honored the Trash preference.

Changes

• js/base.js: skip optimistic \Deleted when viewport metadata nodeleteshow is set (Trash mode).
• lib/Ajax/Application.php: force a full viewport refresh after delete in search mailboxes.
• lib/Indices.php: treat failed move-to-trash (no expunge ACL) as mark-as-deleted rather than a silent no-op.

Test plan

• Enable move-to-Trash in IMP prefs (real Trash folder).
• Search for messages, multi-select results, click Delete.
• Confirm messages leave the search list and appear in Trash.
• Confirm delete from a normal mailbox still moves to Trash.
• Hard-refresh the browser so updated js/base.js is loaded.

[Copilot]

Pull request overview

This pull request fixes inconsistent delete behavior for messages deleted from search results by ensuring Trash-mode deletes behave like normal mailbox deletes (move to Trash / disappear), and by forcing a viewport refresh so session-synthetic search BUIDs don’t leave stale rows behind.

Changes:

• Skip the client-side optimistic \Deleted paint when the viewport is in “Trash mode” (nodeleteshow), relying on server/viewport updates instead.
• Always trigger a full viewport refresh after deletions in search mailboxes so rebuilt result sets and synthetic BUIDs stay consistent.
• When move-to-Trash can’t be attempted due to missing expunge rights, fall back to marking messages as \Deleted (instead of doing nothing).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/Indices.php	Makes Trash move conditional on expunge rights and ensures non-move cases still perform mark-as-deleted cleanup.
lib/Ajax/Application.php	Forces full viewport refresh after deletes when the active mailbox is a search mailbox.
js/base.js	Avoids optimistic \Deleted flag painting when nodeleteshow indicates Trash-mode UI behavior.

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