Add InstallCommandBlock and integrate installer UI

Introduce a full InstallCommandBlock React component (new file) that builds, previews, and copies install commands with support for GitHub/Gitea, Alpine/Advanced modes, ARM flag, resource presets, and dev gating. Integrate it into ScriptDetailModal: compute hasAlpine and installDefaults from script.install_methods, remove the old simple install command UI/handlers, and embed the new component for non-misc scripts. Update ScriptsGrid to allow aborting batch downloads, invalidate downloaded-scripts cache after downloads, and adjust orderedSlugs passed to the modal (prefer newest when no active filters). On the server, make ScriptDownloaderService resolve dev scripts to the ProxmoxVED repository (dev-specific repo path) while preserving explicit repository_url and default repo behavior.

Author: MickLesk