fix: address PR #144 code review feedback

Addresses all concerns raised by Copilot and Codex reviewers:

**Type Safety (Copilot #1)**:
- Remove dynamic property access `logger[logLevel]`
- Use explicit if/else with proper type checking

**Visibility (Codex #1)**:
- Non-retry errors (protobuf, parsing) always log as ERROR
- Remove warn downgrade for unexpected errors

**Defensive Coding (Copilot #3)**:
- Use `String(originalError?.message ?? originalError)`
- Prevents crashes on undefined/null message property

**Scope Creep (Codex #2)**:
- Add stack trace validation to console.log override
- Only suppress logs originating from libsignal module
- Prevents affecting unrelated application logs

**Logic Clarity (Copilot #2)**:
- Clarify that onRetry hooks handle intermediate logging
- Maintain clear distinction between retry vs non-retry errors

https://claude.ai/code/session_01SoNUGBEWbJwWWws3F2fuzh

src/Signal/libsignal.ts

@@ -30,22 +30,29 @@ console.log = function(...args: unknown[]) {
 	if (args.length > 0 && typeof args[0] === 'string') {
 		const msg = args[0]
 
-		// Suppress session lifecycle dumps (cryptographic details on every encrypt/decrypt)
-		if (msg.startsWith('Closing session')) {
-			return
-		}
+		// Check if this log comes from libsignal by examining the call stack
+		// This prevents suppressing unrelated logs from other modules
+		const stack = new Error().stack || ''
+		const isFromLibsignal = stack.includes('libsignal') || stack.includes('session_cipher')
 
-		// Suppress transient decryption errors that are auto-recovered by retry logic
-		// These flood logs during normal operation when sessions are being re-established
-		// Final failures are still logged via our structured logger (see decode-wa-message.ts)
-		if (
-			msg.includes('Session error') ||
-			msg.includes('Bad MAC') ||
-			msg.includes('MessageCounterError') ||
-			msg.includes('Key used already or never filled') ||
-			msg.includes('Failed to decrypt message with any known session')
-		) {
-			return // suppress - our retry system handles these gracefully
+		if (isFromLibsignal) {
+			// Suppress session lifecycle dumps (cryptographic details on every encrypt/decrypt)
+			if (msg.startsWith('Closing session')) {
+				return
+			}
+
+			// Suppress transient decryption errors that are auto-recovered by retry logic
+			// These flood logs during normal operation when sessions are being re-established
+			// Final failures are still logged via our structured logger (see decode-wa-message.ts)
+			if (
+				msg.includes('Session error') ||
+				msg.includes('Bad MAC') ||
+				msg.includes('MessageCounterError') ||
+				msg.includes('Key used already or never filled') ||
+				msg.includes('Failed to decrypt message with any known session')
+			) {
+				return // suppress - our retry system handles these gracefully
+			}
 		}
 	}