Revert to JdbcTemplate for schema init, keep comment-stripping fix

The DriverManager-based approach likely failed because the ClickHouse
JDBC driver wasn't registered with DriverManager. The original
JdbcTemplate approach worked for route_diagrams and agent_metrics —
only route_executions was skipped due to the comment-parsing bug.

Reverts to simple JdbcTemplate-based init with unqualified table names
(DataSource targets cameleer3 database). The CLICKHOUSE_DB env var on
the ClickHouse container handles database creation.

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

cameleer3-server-app/src/main/resources/clickhouse/01-schema.sql

@@ -1,7 +1,7 @@
 -- Cameleer3 ClickHouse Schema
 -- Tables for route executions, route diagrams, and agent metrics.
 
-CREATE TABLE IF NOT EXISTS cameleer3.route_executions (
+CREATE TABLE IF NOT EXISTS route_executions (
     execution_id     String,
     route_id         LowCardinality(String),
     agent_id         LowCardinality(String),
@@ -32,7 +32,7 @@ ORDER BY (agent_id, status, start_time, execution_id)
 TTL toDateTime(start_time) + toIntervalDay(30)
 SETTINGS ttl_only_drop_parts = 1;
 
-CREATE TABLE IF NOT EXISTS cameleer3.route_diagrams (
+CREATE TABLE IF NOT EXISTS route_diagrams (
     content_hash     String,
     route_id         LowCardinality(String),
     agent_id         LowCardinality(String),
@@ -42,7 +42,7 @@ CREATE TABLE IF NOT EXISTS cameleer3.route_diagrams (
 ENGINE = ReplacingMergeTree(created_at)
 ORDER BY (content_hash);
 
-CREATE TABLE IF NOT EXISTS cameleer3.agent_metrics (
+CREATE TABLE IF NOT EXISTS agent_metrics (
     agent_id         LowCardinality(String),
     collected_at     DateTime64(3, 'UTC'),
     metric_name      LowCardinality(String),