fix: restore community driver catalog support

[itsDNNS]

Summary

Companion to itsDNNS/docsight#863.

• Restore driver in the catalog schema and local validator.
• Add an inert TEMPLATE-DRIVER with a complete package layout and the shared runtime manifest contract.
• Document driver contributions, connection hints, explicit built-in overrides, module paths and the trusted-code boundary.
• Keep threshold profiles classified as analysis and distinguish fixed main/images from the older tagged release.

Validation

• Catalog tests: 8 passed, 2 subtests passed.
• All 5 manifests pass the restored core contract.
• The template loads through the actual core app, appears in settings and passes the connection endpoint using inert data in a network-isolated test.