refactor: remove ~275 lines of dead code and enable stricter tsconfig

- Delete unused src/cli/ui.ts, remove zod dependency, drop 4 dead functions (logError, handleToolError, getRetryDelay, displayTimingSummary)
- Remove 8 unused types/interfaces and 3 duplicate formatting utils from audit/utils.ts
- Narrow export surface: make 7 message-handler functions private, remove unused audit re-exports, unexport AgentDefinition and path constants
- Remove unused runClaudePrompt params (sessionMetadata, attemptNumber) and update caller
- Enable tsconfig noUnusedLocals, noUnusedParameters, noImplicitReturns, noImplicitOverride, noFallthroughCasesInSwitch

src/temporal/activities.ts

@@ -181,9 +181,7 @@ async function runAgentActivity(
       agentName, // description
       agentName,
       chalk.cyan,
-      sessionMetadata,
-      auditSession,
-      attemptNumber
+      auditSession
     );
 
     // 6.5. Sanity check: Detect spending cap that slipped through all detection layers