Add financial account APIs and account management UI

[theMattCode]

User story

As a user, I want to manage my financial accounts so balances and transactions can be organized by where money or assets are held.

Depends on

• Issue Build finance foundation schema and backend module structure #12

Scope

• Add backend APIs for listing, creating, updating, and archiving financial accounts.
• Support account types: cash, bank, credit, loan, investment.
• Store account name, type, primary currency, active/archive status, and display ordering.
• Add Cockpit server functions for account APIs.
• Add a mobile-first account management route in Cockpit.
• Hide archived accounts from active selection while keeping them visible in history/detail views.

Non-scope

• Balance snapshot entry.
• Ledger entry creation.
• Investment positions.

Acceptance criteria

• User can create each supported financial account type.
• User can edit account metadata.
• User can archive an account.
• Archived accounts are not offered as active targets for new entries.
• Account APIs do not expose backend directly to the browser.