[FIX] composer: set editionMode to inactive when composer is unmounted

[rmbh-odoo]

Description:

Steps to reproduce:

• Open the CF side panel and edit a StandaloneComposer inside a color scale.
• Switch the sheet. The panel closes, so the composer is unmounted.
• Previously, the composer remained in editing mode after unmount.

Current behavior before PR:

• Unmounting the composer did not set editionMode to inactive.
• This caused focus issues in other parts of the UI.

Desired behavior after PR is merged:

• Unmounting the composer sets editionMode to inactive.
• Focus and selection are now properly released.

Task: 5149215

review checklist

• feature is organized in plugin, or UI components
• support of duplicate sheet (deep copy)
• in model/core: ranges are Range object, and can be adapted (adaptRanges)
• in model/UI: ranges are strings (to show the user)
• undo-able commands (uses this.history.update)
• multiuser-able commands (has inverse commands and transformations where needed)
• new/updated/removed commands are documented
• exportable in excel
• translations (_t("qmsdf %s", abc))
• unit tested
• clean commented code
• track breaking changes
• doc is rebuild (npm run doc)
• status is correct in Odoo

[robodoo]