feature/1249: Add support for block comments

[bwinsley]

📑 Summary

Resolves #1249

Allows multi line comments to be added using %%* and *%%

• The first line must begin with %%* for the block comment to be recognised (White space before it is allowed)
• The last line must end with *%% for the block comment to be recognised
• The first line is allowed to also be the last line

📏 Design Decisions

Describe the way your implementation works or what design decisions you made if applicable.

📋 Tasks

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• 📖 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]

🦋 Changeset detected

Latest commit: 4ac998e

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

This PR includes changesets to release 1 package

Name	Type
mermaid	Minor

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commit: 4ac998e

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Build	Status	Details	Updated (UTC)
default (Inspect)	✅ No changes detected	-	Dec 19, 2025, 12:19 AM

[codecov]

Codecov Report

❌ Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 3.56%. Comparing base (7b167cf) to head (4ac998e).

Files with missing lines	Patch %	Lines
packages/mermaid/src/diagram-api/comments.ts	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #7028      +/-   ##
==========================================
- Coverage     3.56%   3.56%   -0.01%     
==========================================
  Files          473     474       +1     
  Lines        47566   47582      +16     
  Branches       734     734              
==========================================
  Hits          1696    1696              
- Misses       45870   45886      +16     

Flag	Coverage Δ
unit	3.56% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/mermaid/src/diagram-api/comments.ts	11.11% <0.00%> (-13.89%)	⬇️

... and 1 file with indirect coverage changes

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[bwinsley]

Hi @sidharthv96, there seems to be an issue with ESLint in the CI for this PR. Is there something I need to do to get this working?