fix(sankey): prevent link thickness changes with showValues

[faeezshaikh]

📑 Summary

Fixes #6632

The bug: When showValues: true, link thickness changed significantly compared to showValues: false.

Resolves #6632

📏 Changes:

• Removed showValues-based changes to nodePadding
• Added vector-effect="non-scaling-stroke" to links
• Added min stroke-width of 1px
• Added test to verify link thickness remains constant

Adding new Unit Test:

The new test ensures link thickness remains within 1px when toggling showValues.

Before the PR

Before (when showValues is True)

Before (when showValues is False)

After the PR

After (when showValues is True)

After (when showValues is False)

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added necessary unit/e2e tests.
• 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• 🦋 If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. Changesets that add features should be minor and those that fix bugs should be patch. Please prefix changeset messages with feat:, fix:, or chore:.

[changeset-bot]

⚠️ No Changeset found

Latest commit: f91e089

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[netlify]

✅ Deploy Preview for mermaid-js ready!

Name	Link
🔨 Latest commit	f91e089
🔍 Latest deploy log	https://app.netlify.com/projects/mermaid-js/deploys/68d15894e336690008f3747a
😎 Deploy Preview	https://deploy-preview-6970--mermaid-js.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[pkg-pr-new]

Open in StackBlitz

@mermaid-js/examples

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/examples@6970

mermaid

npm i https://pkg.pr.new/mermaid-js/mermaid@6970

@mermaid-js/layout-elk

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/layout-elk@6970

@mermaid-js/layout-tidy-tree

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/layout-tidy-tree@6970

@mermaid-js/mermaid-zenuml

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/mermaid-zenuml@6970

@mermaid-js/parser

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/parser@6970

@mermaid-js/tiny

npm i https://pkg.pr.new/mermaid-js/mermaid/@mermaid-js/tiny@6970

commit: f91e089