fix(docs): make the Starlight build pass

## Changes
- Bump @astrojs/starlight to ^0.32.0 so starlight-openapi 0.13's plugin
  contract (top-level setup hook) is supported
- Replace the no-arg docsLoader call with Astro's glob loader pointing
  at ../api-content so prose stays outside the Astro project tree
- Rename introduction.md → index.md and update the sidebar slug so the
  /docs/ root resolves instead of returning 404
- Commit package-lock.json so Vercel installs deterministically

## Verification
- npm run build produces 96 pages (7 narrative + 88 OpenAPI operations + 1
  releases timeline)
- /docs/, /docs/releases/, /docs/api-reference/operations/authlogin/ and
  every other route return 200 locally
- 14 release cards render with the brand-green "Latest" badge on v3.7.1

docs/api/src/content.config.ts

@@ -1,13 +1,23 @@
 import { defineCollection } from "astro:content";
-import { docsLoader } from "@astrojs/starlight/loaders";
+import { glob } from "astro/loaders";
 import { docsSchema } from "@astrojs/starlight/schema";
 
 // Load markdown from a sibling folder so prose lives outside the Astro
 // project tree. Contributors edit /docs/api-content/*.md without touching
 // the build tool.
+//
+// Starlight's built-in docsLoader is hardcoded to src/content/docs/, so we
+// use Astro's plain glob loader with a custom base and apply Starlight's
+// schema on top. The collection name must remain "docs" — Starlight looks
+// it up by that exact name.
 export const collections = {
 	docs: defineCollection({
-		loader: docsLoader({ base: "../api-content" }),
+		loader: glob({
+			base: "../api-content",
+			// README is contributor-facing docs (how to build the site),
+			// not part of the published content.
+			pattern: ["**/[^_]*.{md,mdx}", "!README.md"],
+		}),
 		schema: docsSchema(),
 	}),
 };