feat(chart): add extra env support

[coffeexcoin]

What changed

• Bumped the abstract-node chart version from 0.1.37 to 0.1.38.
• Updated the default external node app/image version from 29.14.0 / v29.14.0 to 29.19.0 / v29.19.0.
• Added node.extraEnv so operators can append arbitrary environment variables to the external node container beyond the chart's preconfigured env vars.

Impact

Chart users can now set additional node environment variables through values without needing to fork or patch the StatefulSet template.

Validation

• helm lint /private/tmp/abstract-node-chart-test.9mSFAy/abstract-node
• helm template abstract-node /private/tmp/abstract-node-chart-test.9mSFAy/abstract-node
• helm template abstract-node /private/tmp/abstract-node-chart-test.9mSFAy/abstract-node --set node.extraEnv.FOO=bar --set node.extraEnv.NUMERIC=123

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PR-Codex overview

This PR updates the abstract-node Helm chart by adding support for additional environment variables, updating version numbers, and modifying configuration for the external node.

Detailed summary

• Added support for extraEnv in statefulset.yaml to allow additional environment variables.
• Updated tag from v29.14.0 to v29.19.0 in values.yaml.
• Incremented version from 0.1.37 to 0.1.38 in Chart.yaml.
• Updated appVersion from 29.14.0 to 29.19.0 in Chart.yaml.

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