feat: implement account switcher component and state management

- Add AccountSwitcher component for managing user accounts with UI for switching, adding, and logging out.
- Create account state manager to handle snapshots of account-specific states for efficient switching.
- Introduce utility functions for account management, including ID generation and avatar color assignment.
- Implement Zustand store for account management, supporting addition, removal, and state retrieval of accounts.

locales/en/common.json

@@ -34,6 +34,9 @@
     "dismiss": "Dismiss",
     "or": "or",
     "sign_in_sso": "Sign in with SSO",
+    "add_account_title": "Add Account",
+    "add_account_subtitle": "Sign in with another account",
+    "cancel": "Cancel",
     "website": "Website",
     "imprint": "Imprint",
     "privacy_policy": "Privacy Policy",
@@ -58,6 +61,11 @@
     "storage_free": "Free",
     "storage_total": "Total",
     "sign_out": "Sign out",
+    "sign_out_of": "Sign out of {account}",
+    "sign_out_all": "Sign out of all accounts",
+    "add_account": "Add account",
+    "set_as_default": "Set as default",
+    "switch_account": "Switch account",
     "contacts": "Contacts",
     "calendar": "Calendar",
     "settings": "Settings",