refactor(packages): extract agents-md-core package

packages/agents-md-core/src/index.ts

@@ -0,0 +1,12 @@
+export { AGENTS_FILENAME } from "./constants";
+export { findAgentsMdUp, resolveFilePath } from "./finder";
+export { formatAgentsMdContextBlock } from "./formatter";
+export { getSessionCache } from "./injection-cache";
+export { processFilePathForAgentsInjection } from "./injector";
+export type {
+  AgentsMdContextOutput,
+  AgentsMdDiscoveryInput,
+  AgentsMdInjectedPathsStorage,
+  AgentsMdTruncator,
+  TruncationResult,
+} from "./types";