feat(suggestions): block auto-fix for AEM Edge sites on PLG and FREE_TRIAL tiers

[ravverma]

Summary

• Blocks the autofixSuggestions endpoint for AEM Edge sites enrolled on PLG or FREE_TRIAL ASO tiers, returning a 403 unauthorized response to the frontend
• Uses TierClient.createForSite + checkValidEntitlement() to resolve both the entitlement tier and active site enrollment — the block only fires when both are present (entitlement tier is PLG/FREE_TRIAL and siteEnrollment is non-null)
• Logs a warn message with the site ID for observability: Auto-fix blocked for site {siteId}: not supported for AEM Edge sites on PLG tier
• Fails open: if the entitlement check itself throws, a warn is logged and the request proceeds normally
• 100% branch and statement coverage on suggestions.js; 3 new tests cover PLG block, FREE_TRIAL block, and the no-enrollment pass-through case

[ravverma]

@solaris007 from review POV,
these two PRs will not be released
#2267
https://github.com/adobe/spacecat-auth-service/pull/557
I have created this one to fix the flow
thanks
cc: @mimchome

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

This PR will trigger a minor release when merged.