feat: add ClickHouse DataSource and JdbcTemplate configuration

Adds ClickHouseProperties (bound to clickhouse.*), ClickHouseConfig
(conditional HikariDataSource + JdbcTemplate beans), and extends
application.yml with clickhouse.enabled/url/username/password and
cameleer.storage.metrics properties.

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

cameleer3-server-app/src/main/java/com/cameleer3/server/app/config/ClickHouseConfig.java

@@ -0,0 +1,34 @@
+package com.cameleer3.server.app.config;
+
+import com.zaxxer.hikari.HikariDataSource;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import javax.sql.DataSource;
+
+@Configuration
+@EnableConfigurationProperties(ClickHouseProperties.class)
+@ConditionalOnProperty(name = "clickhouse.enabled", havingValue = "true")
+public class ClickHouseConfig {
+
+    @Bean(name = "clickHouseDataSource")
+    public DataSource clickHouseDataSource(ClickHouseProperties props) {
+        HikariDataSource ds = new HikariDataSource();
+        ds.setJdbcUrl(props.getUrl());
+        ds.setUsername(props.getUsername());
+        ds.setPassword(props.getPassword());
+        ds.setMaximumPoolSize(10);
+        ds.setPoolName("clickhouse-pool");
+        return ds;
+    }
+
+    @Bean(name = "clickHouseJdbcTemplate")
+    public JdbcTemplate clickHouseJdbcTemplate(
+            @Qualifier("clickHouseDataSource") DataSource ds) {
+        return new JdbcTemplate(ds);
+    }
+}

cameleer3-server-app/src/main/java/com/cameleer3/server/app/config/ClickHouseProperties.java

@@ -0,0 +1,20 @@
+package com.cameleer3.server.app.config;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@ConfigurationProperties(prefix = "clickhouse")
+public class ClickHouseProperties {
+
+    private String url = "jdbc:clickhouse://localhost:8123/cameleer";
+    private String username = "default";
+    private String password = "";
+
+    public String getUrl() { return url; }
+    public void setUrl(String url) { this.url = url; }
+
+    public String getUsername() { return username; }
+    public void setUsername(String username) { this.username = username; }
+
+    public String getPassword() { return password; }
+    public void setPassword(String password) { this.password = password; }
+}