feat(monitor): sign in to a PBS with user and password and add a Tasks tab

- Connect a PBS with user and password, creating a read-only API token
- Never store the password; remove the token when the role cannot be granted
- Show the PBS connection form as a dialog with the project contrast and blue actions
- Move recent tasks and maintenance schedules of a PBS to a new Tasks tab
- Keep the Datastores tab for datastores, disks and pools

AppImage/messages/en/common.json

@@ -10,6 +10,14 @@
     "detectedTitle": "PBS detected in Proxmox storage",
     "detectedHelp": "These Proxmox Backup Servers are configured as backup storage. Connect each one with a read-only API token to see its datastores, tasks and jobs here.",
     "connect": "Connect",
+    "tasksTab": "Tasks",
+    "signInWith": "Sign in with",
+    "methodPassword": "User and password",
+    "methodToken": "API token",
+    "username": "User (user@realm)",
+    "password": "Password",
+    "passwordHelp": "The password is used once to create a read-only API token (Audit role) for this Monitor. Only that token is saved, never the password. Enable Monitor authentication first.",
+    "cancel": "Cancel",
     "refresh": "Refresh",
     "manage": "Manage PBS connections",
     "loadFailed": "Could not load PBS status.",