build(prompts-core): bundle markdown prompt variants

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

packages/prompts-core/src/index.ts

@@ -1,11 +1,17 @@
 export type {
+  BundledPromptSource,
+  FilesystemPromptSource,
   LoadedPrompt,
+  LoadBundledPromptInput,
+  LoadFilesystemPromptInput,
   LoadPromptInput,
   ModelVariant,
   PromptSource,
   RuntimeInjection,
+  SyncRuntimeInjection,
   VariantTable,
 } from "./types"
+export { atlasPromptVariants } from "./atlas-prompts"
 export { resolveVariant } from "./variant-resolver"
 export type { ResolveVariantInput } from "./variant-resolver"
-export { loadPrompt, PromptFileNotFoundError, PromptPathTraversalError } from "./loader"
+export { loadPrompt, loadPromptSync, PromptFileNotFoundError, PromptPathTraversalError } from "./loader"