fix: support memory fragment type and gracefully format validation errors

[jessn-dev]

This pull request addresses two open bugs related to agenticscope.toml manifest validation:

1. Support for Memory Fragments (Closes init scaffolds .scope/memory/ but the manifest schema rejects type = "memory" #3)**

   • Added memory to the FragmentType enum so agenticscope init's default scaffolded .scope/memory/ directory correctly passes schema validation.
   • Updated the type precedence mapping and vendor targets to process and correctly render the new memory fragment type in generated context files.

2. Clean Validation Error Formatting (Closes build dumps a raw ZodError stacktrace on an invalid manifest (lint fails cleanly) #4)**

   • Wrapped loadManifest in a helper function (loadManifestOrExit) across the build, pack, and lint CLI commands.
   • Now, if the manifest violates the Zod schema, the CLI catches the ZodError and elegantly prints the exact validation failures (along with their property paths), rather than instantly crashing and dumping a raw Node stacktrace to the user.

[github-actions]

🎉 This PR is included in version 1.1.1 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀