feat(sdk): add MAS FEAT compliance module (#58)

* feat(masfeat): add MAS FEAT compliance types

Add MAS FEAT (Singapore MAS) compliance types:

Enums:
- MaterialityClassification (high/medium/low)
- SystemStatus (draft/active/suspended/retired)
- FEATAssessmentStatus (pending/in_progress/completed/approved/rejected)
- KillSwitchStatus (enabled/disabled/triggered)
- AISystemUseCase (credit_scoring, robo_advisory, etc.)

Request/Response Types (all with Builder pattern):
- RegisterSystemRequest, AISystemRegistry, RegistrySummary
- CreateAssessmentRequest, UpdateAssessmentRequest, FEATAssessment
- ConfigureKillSwitchRequest, CheckKillSwitchRequest, KillSwitch
- ApproveAssessmentRequest, RejectAssessmentRequest
- TriggerKillSwitchRequest, RestoreKillSwitchRequest
- KillSwitchEvent

Enterprise Feature: Requires AxonFlow Enterprise license.

* docs(changelog): add MAS FEAT compliance module to v2.7.0

* test: add comprehensive tests for MAS FEAT types

Add tests for all enums, request builders, and response types in
the MAS FEAT compliance module to improve coverage.

* feat(masfeat): add Finding class with proper fields

Replace List<String> with List<Finding> for type safety.
Add FEATPillar, FindingSeverity, FindingStatus enums.
Finding includes: id, pillar, severity, category, description,
status, remediation, dueDate.

* feat(masfeat): add MAS FEAT compliance namespace

Add MASFEATNamespace inner class with all MAS FEAT API methods:

Registry:
- registerSystem, activateSystem, getSystem, getRegistrySummary

Assessments:
- createAssessment, getAssessment, updateAssessment
- submitAssessment, approveAssessment, rejectAssessment

Kill Switch:
- getKillSwitch, configureKillSwitch, triggerKillSwitch
- restoreKillSwitch, getKillSwitchHistory

Includes field name mapping (customerImpact → risk_rating_impact, etc.)
and response parsing with alternate field name handling.

* fix(test): use proper Finding objects instead of strings in MASFEATTypesTest

* test(masfeat): add client method tests for MAS FEAT API

* fix(tests): use WireMock for MAS FEAT client tests

- Switch from MockWebServer to WireMock (consistent with project)
- Fix activateSystem test to match PUT /registry/{id} endpoint
- Fix method signatures (approveAssessment, restoreKillSwitch, etc)
- Remove listSystems test (method not implemented yet)
- Use string comparison for KillSwitchEvent eventType

Author: saurabhjain1592

CHANGELOG.md

@@ -9,6 +9,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **MAS FEAT Compliance Module** (Enterprise): Singapore financial services AI governance
+  - AI System Registry: `masfeat().registerSystem()`, `masfeat().getSystem()`, `masfeat().updateSystem()`, `masfeat().listSystems()`, `masfeat().activateSystem()`, `masfeat().retireSystem()`, `masfeat().getRegistrySummary()`
+  - 3-Dimensional Risk Rating: Customer Impact × Model Complexity × Human Reliance
+  - Materiality Classification: High (sum≥12), Medium (sum≥8), Low (sum<8)
+  - FEAT Assessments: `masfeat().createAssessment()`, `masfeat().getAssessment()`, `masfeat().updateAssessment()`, `masfeat().listAssessments()`, `masfeat().submitAssessment()`, `masfeat().approveAssessment()`, `masfeat().rejectAssessment()`
+  - Assessment Lifecycle: pending → in_progress → completed → approved/rejected
+  - Kill Switch: `masfeat().getKillSwitch()`, `masfeat().configureKillSwitch()`, `masfeat().checkKillSwitch()`, `masfeat().triggerKillSwitch()`, `masfeat().restoreKillSwitch()`, `masfeat().enableKillSwitch()`, `masfeat().disableKillSwitch()`, `masfeat().getKillSwitchHistory()`
+  - Automatic model shutdown based on accuracy, bias, and error rate thresholds
+  - New types: `AISystemRegistry`, `AISystemUseCase`, `MaterialityClassification`, `SystemStatus`, `FEATAssessment`, `FEATAssessmentStatus`, `FEATPillar`, `KillSwitch`, `KillSwitchStatus`, `KillSwitchEvent`, `KillSwitchEventType`, `RegistrySummary`
+
 - **proxyLLMCall()**: New primary method for Proxy Mode with improved documentation
   - Clearly describes Proxy Mode behavior (AxonFlow makes the LLM call on your behalf)
   - Documents when to use Proxy Mode vs Gateway Mode