feat(generator): add role, aria-label, and title to root SVG for acce…

[raiyan22]

What does this PR do?

Adds screen-reader accessibility metadata to the root SVG generated by buildSvg().

• Adds role="img" to the root <svg>
• Adds a dynamic aria-label summarizing GitHub contributions and longest streak
• Adds a <title> element as the first child of the root SVG
• Works with both full and minimal layouts

Type of change

• Bug fix
• New feature (new input, new visual variant, etc.)
• Documentation
• Gallery submission (README screenshot)
• Other

Checklist

• I ran node src/generate-constellation.js locally and both
  dist/constellation-dark.svg and dist/constellation-light.svg
  generated without errors.
• If I added/changed an action.yml input, I updated the inputs table in README.md and the DEFAULTS block / doc comment in src/generate-constellation.js.
• I did not add a new runtime dependency.

Screenshots

Not applicable — this change only adds accessibility metadata and does not change the visual appearance.

Related issues

Closes #3

[m3hrab]

PR #5 Review

Approved ✅ - merging now.

@raiyan22 Correct implementation. role="img", aria-label, and <title> added properly. No visual changes.

@yourasmit15-web I noticed your commit 59e7bb4 also addresses the same issue. Appreciate the initiative! Since @raiyan22's PR is already complete and linked to #3, I'm going with this one. Feel free to open a separate PR if you have any additional improvements or a different approach worth exploring.

Minor nit (not blocking):

The summary label currently shows "longest streak 0 days" when a user has no active streak. While this is technically accurate, it might sound a bit awkward. Consider handling this edge case in a follow-up:

const streakText = stats.longest > 0 ? `${stats.longest} days` : 'no streak yet';
const summary = `GitHub contribution constellation: ${totalContributions} contributions, longest streak ${streakText}`;