next.js

b22e5a29 - Rename skill to next-bundle-optimizer and document its usage (#99731)

Rename skill to next-bundle-optimizer and document its usage (#99731) ## Summary Rename `next-browser-initial-load-optimizer` to `next-bundle-optimizer` and update the skill directory, metadata, links, and install commands. Document how to use the skill with Turbopack's bundle analyzer, with prompts for audits, fixes, and route-specific optimization. ## Verification - Prettier passed for the skill and both guides. - Runtime tests not run (docs and skill rename only). <!-- NEXT_JS_LLM -->