Move search api to Worker, and search indexes to R2

[kamilkisiela]

During the docs build, /api/search.json is prerendered and exported as the search index.
The website workflow uploads that index to R2 under search/<github-sha>.json, then deploys the docs Worker with SEARCH_INDEX_KEY=<github-sha>.

At runtime, the docs app still calls /api/search, but the docs Worker intercepts that request and proxies it through the SEARCH_API service binding to the new hive-search-api Worker.
The docs Worker forwards the active SEARCH_INDEX_KEY as x-search-index-key header, and the Search API Worker loads the matching R2 object, creates the Fumadocs search server, and caches it in Worker memory.

PR previews reuse the same Search API Worker but upload and reference their own SHA-specific index.

The generated search index is 3MB raw.

---

Current main ships 25MB file with search related data, that is sent to every user as 6-7mb gzipped content.
Slow 4G network = 26s to load the file.

Now this file is smaller (3MB raw) and sent from R2 to Worker (and cached per cf location), so in case of cold starts (that I try to eliminate with perwarming the cf location), the network has no impact on search performance.

[github-actions]

Deployment	URL
🌐 Website	https://0318d8ea-hive-platform-docs.theguild.workers.dev
📚 Storybook	https://pr-100.the-guild-docs-storybook.pages.dev

[kamilkisiela]

@copilot how to fix this error:

$ bun --bun ./tools/export-search-indexes.ts ./.output/search/latest.json
60 | lastModified?: Date;
61 | },
62 | }
63 | }>({"doc":{"passthroughs":["extractedReferences","_headerImage","_mobileImage","_ogImage","lastModified"]}});
64 |
65 | export const blog = await create.docLazy("blog", "content/blog", import.meta.glob([".//*.{mdx,md}"], {
^
TypeError: import.meta.glob is not a function. (In 'import.meta.glob([".//*.{mdx,md}"], {
base: "./../content/blog",
query: {
collection: "blog",
only: "frontmatter"
},
import: "frontmatter",
eager: !0
})', 'import.meta.glob' is undefined)
at /home/runner/work/docs/docs/packages/documentation/.source/server.ts:65:78

Bun v1.3.5 (Linux x64)
error: script "search:export" exited with code 1

[kamilkisiela]

The default was so low that when I typed "router" it ended end with ro, rout and router http calls, first two were not even cancelled... :D