Explore browser-like navigation for --ui: back history and shareable links

[BlueLabelscotch]

Idea

Make --ui feel a bit more like a browser: add "back" history and a way to jump to a saved view via a link (command = path, flags = query params).

Current state

• Drilldown and cross-command linking already exist (ui_commands YAML, uiLinkTarget).
• No concept of a "link" today; the closest thing is the shell command itself.

Proposal

• Back: turn the implicit one-level back into an explicit []uiLinkTarget history stack — enables multi-level back, forward, and cycle detection. Scope inheritance/reversion falls out for free since each hop already builds a child Ctx.
• Links: the CLI command itself is basically already a "link." Main gaps: views don't currently track the flags/scope that produced them (needed to regenerate the command), links won't portable across different environments/clusters, and renamed flags/verbs could break saved links over time.

Requirements (keep updating with ideas)

• LisPos: stick the #listpos=x, to remember the cursor position in the last click.