Add global account sync message, integrate with family sync flow

[zachgoll]

#585 covered a general flow around triggering account syncs and keeping track of the last account sync. This issue is for displaying a global sync message when one or more accounts are syncing.

See the sync method on Account below for context:

maybe/app/models/account/syncable.rb

Lines 8 to 21 in b3c48d1

	def sync
	update!(status: "syncing")
	sync_exchange_rates
	calculator = Account::Balance::Calculator.new(self)
	calculator.calculate
	self.balances.upsert_all(calculator.daily_balances, unique_by: :index_account_balances_on_account_id_date_currency_unique)
	self.balances.where("date < ?", effective_start_date).delete_all
	update!(status: "ok")
	rescue => e
	update!(status: "error")
	Rails.logger.error("Failed to sync account #{id}: #{e.message}")
	end

Requirements

• Remove sync_message partial and all code that references / renders it. This was originally built as a placeholder.
• Trigger a global notification on either of the following events:
  • A single account sync starts (additional account sync events will be appended as separate notifications)
  • A "family sync" (all accounts at once) starts
• Notification is persistent until the sync completes. At completion, it is updated to a success or failure notification.

• Syncing notification should not interfere with other notifications (if accounts are syncing and user performs an action that triggers a notification, that notification should "stack" underneath the accounts syncing message, which persists until accounts are done syncing)
• Ideally, notifications are triggered directly from the account sync background jobs via Turbo streams

Considerations

• We will have to distinguish between individual account syncs and "family syncs"
  • Individual account syncs will have 1 notification per background job
  • Family syncs will have 1 notification per group of jobs (GoodJob's batches may be helpful here—but not a hard requirement)
• Existing notification UI will need to be extended to support these flows - Extend shared/notification partial to allow persistent notifications with action buttons #597 will cover this

Designs

The following designs show the "family sync" notification flow. Individual account syncs should use the following messages:

• In-progress: "Syncing [account name]"
• Complete: "[account name] sync completed" or "[account name] sync failed"

https://www.figma.com/file/lonJmVk3HYkwZoIO7xYP2w/Maybe-App-(Community)?type=design&node-id=2566-134&mode=design&t=PEYkBK1qYR1Yhw8p-0