docs: update for log forwarding v2 (source field, wire format)

HOWTO.md: log ingestion example updated from LogBatch wrapper to raw
JSON array with source field. CLAUDE.md: added LogIngestionController,
updated LogQueryController with new filters. SERVER-CAPABILITIES.md:
updated log ingestion and query descriptions, ClickHouse table note.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

HOWTO.md

@@ -242,19 +242,18 @@ curl -s -X POST http://localhost:8081/api/v1/data/metrics \
   -H "Authorization: Bearer $TOKEN" \
   -d '[{"agentId":"agent-1","metricName":"cpu","value":42.0,"timestamp":"2026-03-11T00:00:00Z","tags":{}}]'
 
-# Post application log entries (batch)
+# Post application log entries (raw JSON array — no wrapper)
 curl -s -X POST http://localhost:8081/api/v1/data/logs \
   -H "Content-Type: application/json" \
   -H "Authorization: Bearer $TOKEN" \
-  -d '{
-    "entries": [{
-      "timestamp": "2026-03-25T10:00:00Z",
-      "level": "INFO",
-      "loggerName": "com.acme.MyService",
-      "message": "Processing order #12345",
-      "threadName": "main"
-    }]
-  }'
+  -d '[{
+    "timestamp": "2026-03-25T10:00:00Z",
+    "level": "INFO",
+    "loggerName": "com.acme.MyService",
+    "message": "Processing order #12345",
+    "threadName": "main",
+    "source": "app"
+  }]'
 ```
 
 **Note:** The `X-Protocol-Version: 1` header is required on all `/api/v1/data/**` endpoints. Missing or wrong version returns 400.