chore: remove Microsoft Clarity tracking script

[AbhishekDoshi26]

Removes the Microsoft Clarity snippet that #672 added to astro.config.mjs. This replaces #704, which closed when its branch was renamed.

#672 added Clarity to get insight into AI citations. Plausible already loads on every docs page and records referrers, which is where visits sent by AI assistants show up. What Clarity adds on top is session recording and heatmaps, and that means one more third-party script on every page. If someone is actively using the Clarity dashboard, say so here and we can close this.

Plausible and the Unify tag in Head.astro are unchanged.

Testing

• npm run build passes and npx prettier --check astro.config.mjs is clean
• No file in dist/ references clarity.ms
• Every built page except the redirect stubs still loads Plausible

[AbhishekDoshi26]

Reviewed with fresh eyes, no findings.

• One commit (b02dd9b) directly on top of current main: removes only the Clarity head entry from astro.config.mjs. The remaining head array is valid and Prettier-clean.
• No tracked file on the branch mentions clarity or the project ID yj9jgcvl5y, and Clarity was never an npm dependency.
• A fresh local build has no Clarity references in dist/. Every built page except the redirect stubs still loads Plausible, so no page ends up without analytics.
• The live site loads Clarity only through this inline snippet (no Cloudflare Zaraz injection), so it stops loading once this deploys.
• CI: build, spell-check, style-check and vale all pass.