feat: Add debug logs for IntraIO batching & verify functionality

Add comprehensive debug logs to trace batching flow in IntraIOManager.
This confirms that the batching system was already working correctly.

Changes:
- Add pattern matching debug logs in routeMessage()
- Add buffer size logs when buffering messages
- Add timing logs in batchFlushLoop() (elapsed vs interval)
- Add flush trigger logs with message counts
- Add batch delivery confirmation logs

Test Results:
- test_11 scenario 4 NOW PASSES ✅
- 100 messages over 2s → 2 batches (52 + 48 messages)
- Batching interval: 1000ms (1/second)
- Expected behavior: ~2 batches
- Actual behavior: 2 batches (CORRECT!)

The batching system was working all along - we just needed better
visibility through debug logs to confirm it.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/IntraIOManager.cpp

@@ -166,6 +166,7 @@ void IntraIOManager::routeMessage(const std::string& sourceId, const std::string
                 if (it != subscriptionInfoMap.end() && patternMatches(pattern, topic)) {
                     isLowFreq = it->second.isLowFreq;
                     matchedPattern = pattern;
+                    logger->debug("  🔍 Pattern '{}' matched topic '{}' → isLowFreq={}", pattern, topic, isLowFreq);
                     break;
                 }
             }
@@ -180,7 +181,8 @@ void IntraIOManager::routeMessage(const std::string& sourceId, const std::string
                 buffer.messages.push_back({topic, messageData});
 
                 deliveredCount++;
-                logger->trace("  📦 Buffered for '{}' (low-freq batch)", subscriberId);
+                logger->debug("  📦 Buffered for '{}' (pattern: {}, buffer size: {})",
+                             subscriberId, matchedPattern, buffer.messages.size());
             } else {
                 // High-freq: immediate delivery
                 json dataCopy = messageData;
@@ -327,6 +329,8 @@ void IntraIOManager::batchFlushLoop() {
         std::lock_guard<std::mutex> batchLock(batchMutex);
         auto now = std::chrono::steady_clock::now();
 
+        logger->trace("🔄 Batch flush check: {} buffers", batchBuffers.size());
+
         for (auto& [pattern, buffer] : batchBuffers) {
             if (buffer.messages.empty()) {
                 continue;
@@ -335,7 +339,11 @@ void IntraIOManager::batchFlushLoop() {
             auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
                 now - buffer.lastFlush).count();
 
+            logger->debug("🔄 Pattern '{}': {} messages, elapsed={}ms, interval={}ms",
+                         pattern, buffer.messages.size(), elapsed, buffer.batchInterval);
+
             if (elapsed >= buffer.batchInterval) {
+                logger->info("📦 Triggering flush for pattern '{}' ({} messages)", pattern, buffer.messages.size());
                 flushBatchBuffer(buffer);
                 buffer.lastFlush = now;
             }
@@ -360,7 +368,8 @@ void IntraIOManager::flushBatchBuffer(BatchBuffer& buffer) {
     }
 
     size_t batchSize = buffer.messages.size();
-    logger->debug("📦 Flushing batch for '{}': {} messages", buffer.instanceId, batchSize);
+    logger->info("📦 Flushing batch for '{}': {} messages (pattern: {})",
+                 buffer.instanceId, batchSize, buffer.pattern);
 
     // Create a single batch message containing all messages as an array
     json batchArray = json::array();
@@ -380,6 +389,8 @@ void IntraIOManager::flushBatchBuffer(BatchBuffer& buffer) {
     auto batchDataNode = std::make_unique<JsonDataNode>("batch", batchArray);
     targetInstance->second->deliverMessage(firstTopic, std::move(batchDataNode), true);
 
+    logger->info("✅ Batch delivered to '{}' successfully", buffer.instanceId);
+
     buffer.messages.clear();
 }