Fix: height issues with webframe

[BrettJephson]

Updates algorithm for sizing webframe to fix two issues:

1. webframe adding extra space under Mermaid diagrams
2. webframe cutting off content in integration form.

Added another Mermaid diagram to e2e tests to test landscape.

Tested with:
https://gitbook-v2-q3lwp8faq-gitbook.vercel.app/url/mariadb.com/docs/mariadb-cloud#mariadb-cloud-autonomous-resilient-end-to-end-secure (mermaid diagram)
https://gitbook-v2-q3lwp8faq-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open/blocks/integrations (mermaid diagram)
https://gitbook-v2-q3lwp8faq-gitbook.vercel.app/url/payments.govstack.global/10-workflows (mermaid diagrams)
https://gitbook-v2-q3lwp8faq-gitbook.vercel.app/url/mariadb.com/docs/platform/post-download/mariadb-server-12.0.2 (marketo form)

[changeset-bot]

🦋 Changeset detected

Latest commit: 049327c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
gitbook	Patch

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[github-actions]

Summary of the deployments:

Version	URL	Status
Vercel	https://gitbook-v2-hxge8tho9-gitbook.vercel.app	✅
Cloudflare	https://10334ec3-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	2v	2c
GitBook	https://gitbook-v2-hxge8tho9-gitbook.vercel.app/url/gitbook.com/docs	https://10334ec3-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.com/docs
E2E	https://gitbook-v2-hxge8tho9-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open	https://10334ec3-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.gitbook.io/test-gitbook-open

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Build	Status	Details	Updated (UTC)
customers-v2 (Inspect)	👍 Changes approved	1 changed	Oct 24, 2025, 9:22 AM
v2-cloudflare (Inspect)	👍 Changes approved	4 added	Oct 24, 2025, 9:26 AM
v2-vercel (Inspect)	👍 Changes approved	9 changed, 4 added	Oct 24, 2025, 9:25 AM

[clairechabas]

It fixes the height calculation when the iframe content is a form but it regresses back to the original bug on the height calculation for diagrams which have a large width and a small height.

I approve because the bug on the form iframe is more impactful than the one on the diagrams height so if we can't figure out a good fix for both we should fix the first one in priority and tackle the other separately.