ci: Add datasqrl-examples bump and validation workflows

[velo]

Summary

• Add a manual GitHub Actions workflow to validate datasqrl-examples against a selected SQRL CLI image.
• Default the manual validation image to datasqrl/cmd:dev, while still allowing maintainers to pass snapshot images like ghcr.io/datasqrl/cmd:pr-123.
• Dispatch DataSQRL/datasqrl-examples build.yml, locate the downstream run by correlation_id, and wait for it to finish.
• Keep datasqrl-examples validation detached from CircleCI instead of running it as a CircleCI job.
• Allow CircleCI to publish PR images to GHCR with pr-* tags so they can be manually validated by the examples workflow.
• Add a release/manual workflow that opens a PR in datasqrl-examples to bump its SQRL_VERSION.
• Use the dedicated EXAMPLES_BOT_PAT secret for cross-repo examples operations.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 13.35%. Comparing base (e5914ac) to head (56f8276).
⚠️ Report is 11 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #2075   +/-   ##
=========================================
  Coverage     13.35%   13.35%           
  Complexity      841      841           
=========================================
  Files           606      606           
  Lines         17516    17516           
  Branches       2122     2122           
=========================================
  Hits           2340     2340           
  Misses        14960    14960           
  Partials        216      216           

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[ferenc-csaky]

I don't think this should be executed for every PR or commit that makes it into main.

Ideally that would be nice, but IMO in real life that will be just another annoying step we just skip most of the time, and will be red until we release anyways.

WDYT?

[velo]

I don't think this should be executed for every PR or commit that makes it into main.

Ideally that would be nice, but IMO in real life that will be just another annoying step we just skip most of the time, and will be red until we release anyways.

WDYT?

well, if we don't run this on every PR, we will only know it's broken after someone manually checks