Open multiple tabs in browser

[g3Bg2]

Description:
The ability to open multiple tabs in the browser to work on different automations simultaneously.

Tasks:

• design tab system
• implement tab switching
• save tab state
• add close tab functionality
• show unsaved indicator
• handle tab overflow
• test with many tabs

Acceptance Criteria:

• multiple tabs open
• switching instant
• state preserved
• unsaved changes marked