Add social preview image for shared links

[rohans02]

Summary

Adds public/og-image.png, the social preview card.

layout.tsx already declares openGraph.images and twitter.images as https://evm.fate.stability.nexus/og-image.png, and that URL returns 404 today, so sharing a Fate link in Discord, X or LinkedIn produces no preview. The Twitter card is declared summary_large_image, which specifically requires the image.

• 1200x630 PNG, matching the og:image:width and og:image:height the metadata already declares.
• Built from public/icon-512.png (byte-identical source), cropped to the mark's inked box since the asset carries 43px of dead space on each side.
• Light ground rather than dark. The mark is a dark hexagon badge, so against the site's #0a0a0a its silhouette dissolves and only the bear reads. Same contrast finding as the navbar in Replace Fate logo with new mark and fix broken icons #114; here the fix is the ground rather than the asset.
• Accent rule uses #FFC517, the same gold as the Stability Nexus badge at the top of the README.

Verified: npm run build exits 0, the asset exports to out/og-image.png, and the emitted og:image and twitter:image tags resolve to it.

Placeholder pending a version from the designer who produced the mark. The filename is stable, so replacing it is a one-file swap with no code change.

AI Usage Disclosure:

We encourage contributors to use AI tools responsibly when creating Pull Requests. While AI can be a valuable aid, it is essential to ensure that your contributions meet the task requirements, build successfully, include relevant tests, and pass all linters. Submissions that do not meet these standards may be closed without warning to maintain the quality and integrity of the project. Please take the time to understand the changes you are proposing and their impact. AI slop is strongly discouraged and may lead to banning and blocking. Do not spam our repos with AI slop.

Check one of the checkboxes below:

• This PR does not contain AI-generated code at all.
• This PR contains AI-generated code. I have read the AI Usage Policy and this PR complies with this policy. I have tested the code locally and I am responsible for it.

Checklist

• My PR addresses a single issue, fixes a single bug or makes a single improvement.
• My code follows the project's code style and conventions
• If applicable, I have made corresponding changes or additions to the documentation
• If applicable, I have made corresponding changes or additions to tests
• My changes generate no new warnings or errors
• I have joined the Discord server and I will share a link to this PR with the project maintainers there
• I have read the Contribution Guidelines
• Once I submit my PR, CodeRabbit AI will automatically review it and I will address CodeRabbit's comments.
• I have filled this PR template completely and carefully, and I understand that my PR may be closed without review otherwise.

[coderabbitai]

Important

Review skipped

Review was skipped due to path filters

⛔ Files ignored due to path filters (1)

• public/og-image.png is excluded by !**/*.png

CodeRabbit blocks several paths by default. You can override this behavior by explicitly including those paths in the path filters. For example, including **/dist/** will override the default block on the dist directory, by removing the pattern from both the lists.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: b5c22521-e507-41dd-bed3-c2491d76889d

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}