feat: Add saved views and workspaces

[YoungJinJung]

Summary

Add saved views / workspaces to unic for repeated AWS operational workflows.

Why

DevOps and Platform teams repeatedly use the same filters, sorting, and navigation patterns during incidents and daily operations. Saving those views would reduce setup time and standardize team workflows.

Desired behavior

• Save named views/workspaces for recurring workflows
• Include at least:
  • context or context group
  • selected service/feature
  • filter text and sort state when applicable
  • optional incident-oriented presets
• Load a saved view quickly from the CLI/TUI
• Support both personal and future team/shared workflows

Acceptance Criteria

• Users can save and re-open repeated operational views
• Saved views reduce repeated manual filter/setup work
• Persistence format is documented and stable enough for future extension
• Tests cover persistence and navigation/application of saved views
• README and docs are updated