Changes

• Adds experimental.liveContentEntrypoints. With it, live collections can be declared in src/content.config.ts next to build-time collections, as defineCollection({ type: 'live', entrypoint: './src/live/products.ts' }). The entrypoint default-exports defineLiveCollection({ loader, schema }), one live collection per module, so src/live.config.ts isn't needed. It keeps working alongside entrypoints.
• The content config stays sync-only and is never bundled. The astro:content runtime gets a map of lazy import()s of the entrypoints, so the server bundle contains only the live modules and their imports, not build-time loaders. Entrypoints load on first use, which lets them import astro:content without the live.config.ts redirect.
• Sync throws LiveContentConfigError when the flag is off or an entrypoint doesn't exist. Types are generated from each entrypoint's default export into LiveContentConfig, merged with live.config.ts, and live collections are left out of DataEntryMap.
• Without the flag, the generated astro:content module and the types are unchanged.

Testing

• live-loaders.test.ts runs its existing dev and SSR assertions against a new live-loaders-entrypoints fixture, unchanged. It also checks that the server chunks include the entrypoint but not the glob loader or the content config, and that the build fails without the flag.
• New unit tests (units/content-layer/live-entrypoints.test.ts) cover defineCollection() validation, defineLiveCollection() in entrypoints, and lazy loading in getLiveCollection()/getLiveEntry(), including an entrypoint that doesn't export a live collection.
• New type tests (types/define-collection-entrypoint.ts) cover the defineCollection() overload.

Docs

• The flag is documented in its @docs entry in types/public/config.ts, which generates the configuration reference. Content collection guides can be updated when the flag is stable.

/cc @withastro/maintainers-docs for feedback!