test: add comprehensive type tests for 80% coverage (#34)

Adds tests for:
- CostControlTypesTest: Budget types, enums, and request builders
- MoreTypesTest: Core types like PolicyApprovalResult, ClientRequest/Response
- CodeGovernanceTypesTest: All code governance types

Updates coverage threshold from 70% to 75%.

Coverage increased from 68% to 80%.

Fixes #871

Author: saurabhjain1592

pom.xml

@@ -73,7 +73,7 @@
         <nexus-staging-plugin.version>1.6.13</nexus-staging-plugin.version>
 
         <!-- Coverage Threshold -->
-        <jacoco.minimum.coverage>0.70</jacoco.minimum.coverage>
+        <jacoco.minimum.coverage>0.75</jacoco.minimum.coverage>
     </properties>
 
     <dependencies>