Add handbook docs.json manifest and CI automation for PF MCP collection

[patternfly-jira-sync]

Add UXD AI Handbook standards to the PF MCP as a collection, with the handbook repo maintaining a generated docs.json manifest that the MCP consumes.

Acceptance Criteria:

• scripts/generate-docs-json.sh generates a JSON manifest from handbook docs/ markdown frontmatter

• docs.json contains metadata and raw GitLab URLs for each handbook doc in PF MCP collection format

• CI job regenerates docs.json on merge to main when docs/** files change

• CI job also runs on a weekly scheduled pipeline as a safety net

• MCP-side collection handler fetches docs.json and indexes handbook content alongside PF docs

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Jira Issue: PF-4574