[Bug]: Timeseries request times out when unit(s) parameter specified

Describe the bug

When the unit or units parameter is specified as a unit like ft the request times out with a 408 error. This was discovered by using shefParser which uses these type requests a lot.

Expected behavior

It should return the data in the requested units.

To Reproduce

In test GET /cwms-data/timeseries?office=MVP&name=Baldhill_Dam.Elev.Inst.15Minutes.0.rev-NGVD29&unit=ft will eventually timeout with a 408.

GET /cwms-data/timeseries?office=MVP&name=Baldhill_Dam.Elev.Inst.15Minutes.0.rev-NGVD29 returns as expected.

Priority

High

Logs/Incident Identifier

ERROR: CDA Error: response=<Response [408]>
WARNING: Skipping time series [Baldhill_Dam.Elev.Inst.15Minutes.0.rev-NGVD29]: error fetching from CDA: CWMS API Error (CDA_SERVER/mvp-data/timeseries?office=MVP&name=Baldhill_Dam.Elev.Inst.15Minutes.0.rev-NGVD29&unit=ft&begin=2026-08-24T11%3A37%3A03.091932&end=2026-08-26T11%3A37%3A03.091932&page-size=300000&trim=True). {"message":"Request is taking too long; try narrowing the date range.","incidentIdentifier":"c8552fee-d73e-4573-b7ba-3147d4c53463","source":"Unknown","details":{}}
(CDA_SERVER/mvp-data/timeseries?office=MVP&name=Baldhill_Dam.Elev.Inst.15Minutes.0.rev-NGVD29&unit=ft&begin=2026-08-24T11%3A37%3A03.091932&end=2026-08-26T11%3A37%3A03.091932&page-size=300000&trim=TrueERROR: CDA Error: response=<Response [408]>

CURL Commands

CDA Version

2026.08.14-testa

Additional context

GPT 5.4 suggests the fix is to keep direct-read, but change the unit handling:

• Treat unit/units as response units, not storage-row filters.
• Resolve EN/SI to a concrete response unit as CDA already does.
• Validate only that native unit -> requested unit is convertible.
• Fetch rows in the series native/source unit.
• Convert VALUE to the requested response unit during query or immediately after fetch.
• Keep the response metadata units field set to the requested unit.