Update terraform-policy skill for tfpolicy 0.1.x and 0.2.0+ compatibility

[vpaul97]

Summary

• document mandatory policy.required_providers usage for .policy.hcl when using tfpolicy 0.2.0+
• document best-effort validation behavior for version ranges
• document wildcard schema-validation limitations
• document tfpolicy test schema-verification caveat observed with tfpolicy 0.2.0
• add version-aware skill guidance so the skill branches between tfpolicy 0.1.x and 0.2.0+

Changes

• updated plugins/terraform/skills/terraform-policy/SKILL.md
• updated plugins/terraform/skills/terraform-policy/README.md
• updated plugins/terraform/skills/terraform-policy/references/tfpolicy-author.md
• updated plugins/terraform/skills/terraform-policy/references/tfpolicy-test.md
• updated plugins/terraform/skills/terraform-policy/references/verified-syntax.md

Notes

• tfpolicy 0.1.x does not require policy { required_providers { ... } }
• tfpolicy 0.2.0+ requires top-level policy { required_providers { ... } } for .policy.hcl validation
• version-range validation is best effort
• wildcard targets such as resource_policy "*" are not schema-validated
• tfpolicy test may warn that resource types were not verified against provider schemas even when tfpolicy validate succeeds separately
• the skill now instructs the agent to check CLI version first and provide version-specific guidance

Validation

./scripts/validate-structure.sh
git diff --check

[gautambaghel]

@vpaul97 - instead of hardcoding the provider version you should write the reasoning for it and give the AWS one here as an example

[vpaul97]

Put the reasoning in the 'Block' section above and wrote further reasoning with the aws example 👍 Let me know if this works better!

[gautambaghel]

LGTM!

[leefowlercu]

Looks good to me! Thanks for the update V!