ci: refactor charm-e2e-tests workflow to use k8s-ci CLI

[Copilot]

Description

The charm-e2e-tests.yaml workflow contains numerous bash steps that are difficult to reproduce locally and maintain.

Solution

Introduced k8s-ci charm integration-test command that encapsulates workflow logic:

New CLI command (ci/cmds/charm.py):

• Configures LXD, creates snap tarball, installs tooling (charmcraft/juju)
• Downloads charms, bootstraps Juju controller, clones k8s-operator
• Executes integration tests with tox
• Collects debug artifacts on failure
• Adds timeout protection (600s default, configurable/unlimited for tests)

Workflow simplification (.github/workflows/charm-e2e-tests.yaml):

• Reduced from 160 to 101 lines by replacing 6+ bash steps with single CLI invocation
• Updated Python 3.10 → 3.12

Usage:

tox -e k8s-ci -- charm integration-test \
  --k8s-snap-path "/path/to/k8s.snap" \
  --charm-channel "latest/edge" \
  --arch "amd64" \
  --k8s-operator-ref "main" \
  --workspace "$PWD"

Issue

N/A

Backport

No backport needed - CI tooling change only.

Checklist

• PR title formatted as type: title
• Covered by unit tests - Not applicable, CLI integration command
• Covered by integration tests - Command runs existing integration tests
• Documentation updated - CLI self-documenting via --help
• CLA signed
• Backport label added if necessary - N/A

Original prompt

We have an existing workflow "charm-e2e-tests.yaml". That executes the k8s-snap in the k8s-operator context.

This contains a lot of bash steps and is hard to reproduce/run locally.

Refactor this workflow to use the k8s-ci charm CLI. It should create a new k8s-ci charm integration-test with the necessary flags (k8s-snap-path etc)

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[ethandcosta]

nice refactor, LGTM