fix: align server with protocol v2 chunked transport spec

- ChunkIngestionController: /data/chunks → /data/executions (matches
  PROTOCOL.md endpoint the agent actually posts to)
- ExecutionController: conditional on ClickHouse being disabled to
  avoid mapping conflict
- Persist originalExchangeId and replayExchangeId from ExecutionChunk
  envelope through to ClickHouse (was silently dropped)
- V5 migration adds the two new columns to executions table

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

cameleer3-server-app/src/main/resources/clickhouse/V5__replay_fields.sql

@@ -0,0 +1,2 @@
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS original_exchange_id String DEFAULT '';
+ALTER TABLE executions ADD COLUMN IF NOT EXISTS replay_exchange_id String DEFAULT '';