#799 kgoss: Add GOSS_KUBECTL_RUN_OPTS for kubectl run-specific options

[tyrantkhan]

Fixes #799

Checklist
[X] Documentation is changed or added (if applicable)

Description of change

Adds GOSS_KUBECTL_RUN_OPTS environment variable for options that should only be passed to kubectl run, not to other kubectl commands like wait, cp, exec, or delete.

This is needed because --overrides is only valid for kubectl run, but GOSS_KUBECTL_OPTS is passed to all kubectl commands, causing errors like:

error: unknown flag: --overrides
See 'kubectl wait --help' for usage.

Common use cases:

• Setting serviceAccountName for imagePullSecrets (private registries)
• Setting nodeSelector for architecture-specific scheduling
• Setting tolerations for tainted nodes

Example:

GOSS_KUBECTL_RUN_OPTS='--overrides={"spec":{"serviceAccountName":"my-sa"}}' kgoss run -i myimage:tag

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📚 Documentation preview 📚: https://goss--1044.org.readthedocs.build/en/1044/