fix(opentofu): surface validation step failures

[xnoto]

Summary

• remove continue-on-error from OpenTofu test setup and validation steps so GitHub Actions renders the originating step as failed
• keep same-repository PR reporting with always()
• continue the full pre-commit run after a docs-key failure when checkout, config fetch, and OpenTofu initialization succeeded
• remove the redundant terminal Mark validation failed step

Root cause

continue-on-error: true preserved each step's outcome as failure but converted its displayed conclusion to success. The terminal marker then failed the job, obscuring the originating step.

Compatibility and safety

• no reusable-workflow inputs, secrets, runner labels, plan/apply behavior, or fork protections change
• failure reporting remains restricted to same-repository PRs
• no credentials or sensitive values are added

Validation

GitHub Actions CI is the validation authority; no local OpenTofu operation was run.

[github-actions]

Shared Workflows CI

Shared workflows CI passed.

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View run output

[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Initializing environment for https://github.com/gitleaks/gitleaks.
[INFO] Initializing environment for https://github.com/rhysd/actionlint.
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/gitleaks/gitleaks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/rhysd/actionlint.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
check for case conflicts.................................................Passed
check for merge conflicts................................................Passed
check for broken symlinks............................(no files to check)Skipped
check vcs permalinks.....................................................Passed
detect destroyed symlinks................................................Passed
detect private key.......................................................Passed
mixed line ending........................................................Passed
trim trailing whitespace.................................................Passed
Detect hardcoded secrets.................................................Passed
Lint GitHub Actions workflow files.......................................Passed