feat: create cameleer-clickhouse image with init and config baked in

Bakes init.sql, users.xml (with from_env password), and prometheus.xml
into a custom ClickHouse image to eliminate 3 bind-mounted config files.

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

docker/cameleer-clickhouse/users.xml

@@ -0,0 +1,16 @@
+<clickhouse>
+  <users>
+    <default remove="remove">
+    </default>
+
+    <default>
+      <profile>default</profile>
+      <networks>
+        <ip>::/0</ip>
+      </networks>
+      <password from_env="CLICKHOUSE_PASSWORD" />
+      <quota>default</quota>
+      <access_management>0</access_management>
+    </default>
+  </users>
+</clickhouse>