Dashboard management via cli

[ivpusic]

Added commands to manage dashboards via Dune CLI. AIs will be using it with the help of skill in PR.

[cursor]

PR Summary

Medium Risk
Adds new CLI surface area that calls dashboard create/update/archive APIs and upgrades the API client dependency, which could introduce behavioral changes or edge-case regressions in request/response handling.

Overview
Introduces a new top-level dashboard (alias dash) command, wiring it into cli/root.go and advertising dashboard management in the CLI capability text.

Adds subcommands to create, get (by ID or --owner/--slug), update (flag-driven partial metadata updates plus full widget replacement via JSON flags), and archive dashboards, with consistent -o json support.

Bumps github.com/duneanalytics/duneapi-client-go from v0.4.7 to v0.4.8 to support the new dashboard API calls.

^{Reviewed by Cursor Bugbot for commit 329afd1. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is ON. A cloud agent has been kicked off to fix the reported issue.}

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit 329afd1. Configure here.}