fix(screener): correct icon, restrict move/add, batch triage requests

[krantheman]

Fixes a few Screener bugs:

• Icon: the Screener's eye icon is now authoritative in getIcon, so a stray Mailbox Settings icon can't make it render as a generic folder.
• Move/Add: the Screener (a system folder) is excluded from the move-to / add-to target lists and from the Folders management list.
• Batching: Block/Allow now batch into one request per burst, so screening senders in quick succession no longer fires concurrent automation-sieve rebuilds that race on the shared script (CannotChangeConstantError).

Also renames SCREENING_MAILBOX_NAME → SCREENER_MAILBOX_NAME and mailboxIds.screening → .screener for naming consistency.

🤖 Generated with Claude Code

[greptile-apps]

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The latest batching path submits allow and screen-out actions independently.
• The renamed Screener identifiers are used consistently in the inspected changed files.

Important Files Changed

Filename	Overview
frontend/src/pages/ScreenerView.vue	Adds delayed batching for Screener allow and screen-out actions, with independent handling for each action type.
frontend/src/stores/user.ts	Renames the derived Screener mailbox id key and maps it from the Screener mailbox name.
frontend/src/components/Settings/FolderSettings.vue	Filters the Screener out of the folder management list.
frontend/src/utils/index.ts	Makes the Screener eye icon take priority over stored custom folder icons.
mail/api/mail.py	Updates backend screening mailbox lookups to use the renamed Screener constant.
mail/api/sieve.py	Renames the Screener mailbox constant and applies it to mailbox creation and folder-path lookup.

_{Reviews (3): Last reviewed commit: "style(sieve): apply ruff-format to backf..." | Re-trigger Greptile}