feat: log forwarding v2 — accept List<LogEntry>, add source field

Replace LogBatch wrapper with raw List<LogEntry> on the ingestion endpoint.
Add source column to ClickHouse logs table and propagate it through the
storage, search, and HTTP layers (LogSearchRequest, LogEntryResult,
LogEntryResponse, LogQueryController).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/clickhouse/init.sql

@@ -357,6 +357,9 @@ ORDER BY (tenant_id, timestamp, environment, application, instance_id)
 TTL toDateTime(timestamp) + INTERVAL 365 DAY DELETE
 SETTINGS index_granularity = 8192;
 
+-- Add source column for log forwarding v2 (app vs agent logs)
+ALTER TABLE logs ADD COLUMN IF NOT EXISTS source LowCardinality(String) DEFAULT 'app';
+
 -- ── Usage Events ────────────────────────────────────────────────────────
 
 CREATE TABLE IF NOT EXISTS usage_events (