refactor(corecmd): rename package and finish ContractFinal leaf migration

Move cmdcore to corecmd, declare attendance ContractFinal in helpers, keep
Sheet destructive commands --yes-only, and align catalog/policy provenance.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/generator/cmd_schema_agent_metadata/main.go

@@ -457,7 +457,7 @@ func validateSelectionHintInput(rootPath, hintsDir string, registry commandRegis
 		expectedTools[canonical] = true
 	}
 	// Declared tools carry selection fields in the Contract final overlay
-	// (cmdcore.SchemaDecl) and are exempt from hint-file coverage.
+	// (corecmd.SchemaDecl) and are exempt from hint-file coverage.
 	for canonical := range expectedTools {
 		bound, ok := registry.Bound.ByCanonical[canonical]
 		if ok && cli.HasRuntimeContractFinal(bound.PrimaryCommand) {