fix(typescript): resolve compilation errors for production build

Fixes 4 TypeScript compilation errors preventing successful build:

## Errors Fixed

### 1. lid-mapping.ts:799 - Property 'metricsModule' does not exist
**Error**: `this.metricsModule = null` in destroy() but property never declared
**Fix**: Removed orphaned line from previous metrics cleanup
**Impact**: Allows successful compilation

### 2-3. socket.ts:795,817 - Connection handler type mismatch
**Error**: `{ connection: any }` not assignable to `Partial<ConnectionState>`
**Cause**: Destructuring makes 'connection' required but it's optional in Partial
**Fix**: Changed handlers to `(update: Partial<ConnectionState>)`
**Impact**: Proper type safety for connection.update events

### 4. event-buffer.ts:430 - Wrong argument order
**Error**: Object passed as second arg but logger expects (obj, msg) order
**Fix**: Swapped arguments to `logger.debug({ queuedCount }, 'message')`
**Impact**: Matches logger signature from structured-logger.ts

## Root Cause Analysis

All errors stem from incremental changes where:
- Removed metrics support but missed cleanup reference
- Added connection handlers without checking Partial<T> semantics
- Used logger without verifying parameter order

## Testing

Build verification:
```bash
npm run build  # Should now complete successfully
```

These are compilation errors only - no runtime behavior changes.

https://claude.ai/code/session_VMxqX

src/Signal/lid-mapping.ts

@@ -795,9 +795,6 @@ export class LIDMappingStore {
 		// Clear cache
 		this.mappingCache.clear()
 
-		// Clear metrics module reference
-		this.metricsModule = null
-
 		this.logger.debug('LIDMappingStore destroyed successfully')
 	}