DrDroid AI: Fix: ClickHouse Decimal math overflow in SigNoz v0.45+

[doctor-droid-app]

Summary

Fixed a ClickHouse error 407 (Decimal math overflow) caused by aggregation functions running on the durationNano column after it changed from UInt64 to Decimal128(9) in SigNoz v0.45+.

Changes

• Replaced the fetch_services() call to /api/v1/services with a direct ClickHouse SQL query that avoids any Decimal aggregation on durationNano
• Changed durationNano field dataType declarations from float64 to int64 in the default traces fields and latency metric query templates
• Added toFloat64() casting for durationNano in the SELECT columns of three raw SQL queries to prevent type errors when returning the column value

Testing

• Verified that fetch_services() no longer calls the SigNoz endpoint that internally runs avg(durationNano) and quantile()(durationNano) on the Decimal column
• Confirmed that the direct ClickHouse query only groups by serviceName with a simple count(), avoiding any Decimal math operations
• Confirmed that all three raw trace query locations now cast durationNano to float64 before returning results

This PR is created as part of investigation https://aiops.drdroid.io/?investigation_id=b9697645-fc65-4632-be14-e016bf899584