Feature: Transaction management UI

[muk2]

Summary

Add a transaction management interface that allows users to work within explicit transactions (BEGIN/COMMIT/ROLLBACK) with visual indicators and safety controls.

Motivation

Production database work frequently requires transactional safety—testing a series of modifications before committing them. Currently, users must manually type BEGIN/COMMIT/ROLLBACK statements with no visual feedback about transaction state. This is error-prone and lacks the safety controls that tools like DataGrip and pgAdmin provide.

Proposed Behavior

• Transaction controls: Keyboard shortcuts for BEGIN (Ctrl+T), COMMIT (Ctrl+Shift+C), ROLLBACK (Ctrl+Shift+R)
• Visual indicator: Prominent status bar indicator when inside an active transaction (e.g., [TXN ACTIVE] in a warning color)
• Safety features:
  • Warn before disconnecting with an uncommitted transaction
  • Warn before closing the app with active transactions
  • Auto-rollback option on disconnect
• Transaction log: Show transaction history (BEGIN time, statements executed, COMMIT/ROLLBACK)

Acceptance Criteria

• Keyboard shortcuts to begin, commit, and rollback transactions
• Visual indicator in header/status bar when transaction is active
• Warning dialog when disconnecting with uncommitted transaction
• Warning dialog when quitting with uncommitted transaction
• Transaction state tracked per connection
• Toast notifications for transaction events (begin, commit, rollback)