fix(timeline): wrap long timeline titles properly

[nour0205]

📑 Summary

This PR fixes a layout bug in the Mermaid Timeline diagram where long titles do not wrap and instead overflow or shrink the diagram unnecessarily. The fix introduces robust text wrapping using SVG logic and proper positioning of the title block.

Resolves #6393

📏 Design Decisions

Replace the single element used for the diagram title with a group that contains dynamically calculated elements.
Implemented a wrapText utility in svgDraw.js that:
Splits the title string by whitespace.
Appends new lines when the current line exceeds the maximum width.
Maintains proper line height and alignment.
Centered the title visually by adjusting the x position based on the diagram’s width and manually shifting the group with text-anchor: middle.
Kept the implementation fully SVG-native (no ) for cross-browser consistency and to match Mermaid’s rendering style

📋 Tasks

Make sure you

• [x ] 📖 have read the contribution guidelines
• [x ] 💻 have added necessary unit/e2e tests.
• [x ] 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• [x ] 🦋 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:.

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commit: dd16d30

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 40 lines in your changes missing coverage. Please review.

Project coverage is 3.87%. Comparing base (5e2870f) to head (dd16d30).

Files with missing lines	Patch %	Lines
packages/mermaid/src/diagrams/timeline/svgDraw.js	0.00%	22 Missing ⚠️
.../mermaid/src/diagrams/timeline/timelineRenderer.ts	0.00%	18 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #6405      +/-   ##
==========================================
- Coverage     3.87%   3.87%   -0.01%     
==========================================
  Files          413     412       -1     
  Lines        43216   43238      +22     
  Branches       665     665              
==========================================
  Hits          1675    1675              
- Misses       41541   41563      +22     

Flag	Coverage Δ
unit	3.87% <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
.../mermaid/src/diagrams/timeline/timelineRenderer.ts	0.38% <0.00%> (-0.02%)	⬇️
packages/mermaid/src/diagrams/timeline/svgDraw.js	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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Build	Status	Details	Updated (UTC)
default (Inspect)	⚠️ Changes detected (Review)	10 removed, 10 failures	Apr 30, 2025, 9:30 PM

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