Validate every discovered Mermaid block and return the diagnostics per block.
This is the composable, returns-data entry point — it registers no tests, so
callers (and tests) can assert on the results directly.
Diagnostics are unfiltered: both syntax errors (severity error) and semantic
findings (severity warning or error, per the resolved rules) are included.
Use selectFailures to apply a strict policy.
Validate every discovered Mermaid block and return the diagnostics per block. This is the composable, returns-data entry point — it registers no tests, so callers (and tests) can assert on the results directly.
Diagnostics are unfiltered: both syntax errors (severity
error) and semantic findings (severitywarningorerror, per the resolved rules) are included. Use selectFailures to apply astrictpolicy.