fix: ClickHouse auth credentials and non-fatal schema init

- Set CLICKHOUSE_USER/PASSWORD via k8s secret (fixes "disabling network
  access for user 'default'" when no password is set)
- Add clickhouse-credentials secret to CI deploy + feature branch copy
- Pass CLICKHOUSE_USERNAME/PASSWORD env vars to server pod
- Make schema initializer non-fatal so server starts even if CH is
  temporarily unavailable

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

deploy/base/server.yaml

@@ -79,6 +79,16 @@ spec:
               value: "true"
             - name: CLICKHOUSE_URL
               value: "jdbc:clickhouse://clickhouse.cameleer.svc.cluster.local:8123/cameleer?async_insert=1&wait_for_async_insert=0"
+            - name: CLICKHOUSE_USERNAME
+              valueFrom:
+                secretKeyRef:
+                  name: clickhouse-credentials
+                  key: CLICKHOUSE_USER
+            - name: CLICKHOUSE_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: clickhouse-credentials
+                  key: CLICKHOUSE_PASSWORD
             - name: CAMELEER_STORAGE_METRICS
               value: "postgres"