[piyusshhjangid]

Closes #277

Summary

Adds the saas-deprecation template for announcing a deprecated API, feature, or version and its replacement.

• Shows the deprecated name with a strikethrough, an arrow, and the replacement.
• Includes optional sunset date, migration note, and site name at the bottom.
• Hides blank optional fields and the arrow when the replacement is empty.
• Shrinks and truncates long names; darkens accent text on light backgrounds.
• Registers and exports the template, with tests for rendering and optional fields.

How I tested this

• npm run check — passed with 0 errors and 0 warnings.
• npm run test -- --testTimeout 15000 — 1,401 tests passed.
• npm run build — passed.
• git diff --check — passed.
• Rendered and reviewed the light-background preview with a pale yellow accent; attached the PNG.

AI assistance

OpenAI Codex assisted with implementation, tests, and validation. I reviewed the changes.

Type of Change

• New template

Checklist

• This PR targets dev
• I was assigned the linked issue
• npm run check passes
• npm run test passes
• npm run build passes
• Screenshot included
• New template follows the Template Guidelines

[anurag629]

Thanks @piyusshhjangid, this works. Check, all 1401 tests and the build pass on top of dev with the default timeout, and the renders look right: default, a white background with a pale accent, long caps names, date and note, no replacement (the arrow and "Use instead" go with it), and no sunset date.