postbird v1.1.0 — layout + spaces toolbar, one-command setup

Adds the spaces-toolbar component, folder-pane header hiding, message-header
tidy-up, and PowerShell tooling: deploy.ps1 now applies CSS + recommended prefs
(user.js) + recommended layout (XULStore) in one command. See CHANGELOG.md.

postbird v1.0.0 — Postbox "Monterail Dark" theme for Betterbird 140

First complete theme. All seven v1.0 regions plus the email body. Targets
Betterbird 140.12.0esr-bb24. See CHANGELOG.md.