New design, theme preview & password manager

• A fresh look throughout: all five themes with gradient accents, tinted surfaces and subtle glows. In light mode the palettes are now clearly distinct
• Theme picker with preview cards in Settings
• Redesigned stacks screen: colorful monogram tiles, ring gauges for CPU/RAM/disk and filter chips (All / Running / Stopped / Update / Archive). Stopped stacks start right from a button
• Image Watcher: scheduled auto-updates per image (immediate, at a fixed time, or ignore) with a waiting indicator. Dockge itself is never auto-updated
• Login now supports password managers and iCloud Keychain; 2FA codes are suggested automatically
• One SSH access can be linked to multiple Dockge instances on the same machine
• French and Spanish translations
• Backup: an “Overdue” badge when the last backup is older than the interval
• Saved credentials are reused reliably — no more re-login after a brief connection drop or returning from the background
• Updated in-app links (website, support, privacy)