feat: Add support for project felt

[jschuler]

Summary

• Add support for dynamic GitHub directory expansion in the docs catalog, enabling project-felt/ai-guidelines content to be
  resolved at startup from a single stub entry in docs.json
• Introduce expandGithubDirectory catalog stub type that lists Markdown files via the GitHub Contents API and expands them into
  concrete catalog rows
• Add project-felt URLs to the fetch allowlist
• Gracefully degrade when GitHub API is unreachable or returns an empty directory — the server starts with the remaining catalog
  instead of crashing

Changes

• catalog.expandGithubDirectory.ts (new) — Core expansion logic: fetches a GitHub directory listing, filters for Markdown
  files, and maps each file to a resolved catalog doc. Includes a repo allowlist for defense in depth. Logs a warning instead of
  throwing on empty directories.
• docs.embedded.ts — New types: PatternFlyMcpDocsCatalogDocStub, ExpandGithubDirectoryConfig,
  PatternFlyMcpDocsCatalogSource to model stub entries and the import-time catalog shape.
• docs.json — Added AiGuidelines entry with an expandGithubDirectory stub pointing to
  project-felt/ai-guidelines/content.
• patternFly.getResources.ts — Calls expandGithubDirectoryInCatalog after loading the catalog. On failure, strips
  unresolved stubs and returns the catalog with isFallback: true.
• options.defaults.ts — Added project-felt GitHub URLs to the allowlist.
• resource.patternFlyDocsTemplate.ts / tool.patternFlyDocs.ts — Narrowed .filter(Boolean) to proper type guards
  since entries may now lack a path field.
• Tests — Added aiGuidelines.catalog.test.ts, catalog.expandGithubDirectory.test.ts, fixture data, scoped fetch mock
  helper, and updated existing tests for the new catalog shape.

Test plan

• npx jest — all unit tests pass
• Verify server starts without network access (fallback path)
• Verify AiGuidelines entries appear in search results and resource listings
• Confirm expansion allowlist rejects repos not in the list

[cdcabrera]

@jschuler aspects of this work are available

• without the need for "feat" work
• currently in progress under API work

I'm going to shut this down, because it requires an issue first

[jschuler]

@cdcabrera can you provide more information on where aspects of this work are available?

Also generally it is better to keep a PR open and ask for an Issue to be created. It comes across as rude otherwise.