Add OpenGraph and Twitter meta tags to index.html

[adityaraut649]

Purpose / Description

Add Open Graph and Twitter Card meta tags to web/index.html so shared Observal links display rich previews with a title, description, and image on platforms such as Slack, Discord, and X.

Fixes

Fixes #1356

Approach

Added og:title, og:description, og:image, og:url, og:type and twitter:card, twitter:title, twitter:description, twitter:image meta tags to the section of web/index.html.

How Has This Been Tested?

Ran pnpm build from the web package.
Verified that the build completed successfully without errors.
Confirmed that icon.png exists in web/public.

[CLAassistant]

All committers have signed the CLA.

[adityaraut649]

#1356

[Haz3-jolt]

Two issues to address:

1. Unintended lockfile addition: web/pnpm-lock.yaml was previously removed from the repo and this PR re-introduces it (5,235 lines). Adding OG meta tags to index.html should not require a lockfile change since no new dependencies are involved. Please remove it from the commit.

2. Commit message format: The project uses Conventional Commits. Please rewrite the commit message, e.g. feat(web): add OpenGraph and Twitter meta tags to index.html.

The HTML changes themselves look good. Thanks for contributing!

[adityaraut649]

Thanks for the review! I've removed pnpm-lock.yaml from the PR and updated the commit message to follow the Conventional Commits format.

[adityaraut649]

Fixed the requested changes. Please take another look.