Insight API improvements

Insights API updates to improve Terraform and IaC compatibility and add full resource lifecycle support.

Changes:

• Added insight operations GET, POST, and DELETE on /insights/v1/results/source/{sourceID}/insight/{insightKey}. You can now read, create/update, and delete one insight by key without relying on bulk-only flows or UI redirects.
• Replaced unimplemented page / pageSize with pageToken and maxResults on list and resource-results endpoints, to align with other DoiT APIs. Large resource-result sets must be walked with tokens.
• Changed field provider to cloudProvider.
• ResourceResults is no longer a discriminated oneOf, each item is a single ResourceResult object with optional fields, using resultType to tell you which fields apply.
• Money- and score-like numbers are documented and served as double-precision values so automated tools (e.g. Terraform) do not see spurious drift from rounding.

Implementation steps:

• Update any clients or generated code that uses provider to use cloudProvider.
• Adopt the flattened ResourceResult model.
• Switch to cursor pagination.
• Use the new singular routes where you need stable read/create/delete behavior.