feat(proto): Add GetLocationAsTimeseries route

[devsjc]

Contribution Checklist

• Have you followed the Open Climate Fix Contribution Guidelines?
• Have you referenced the Issue this PR addresses, where applicable?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added a summary of the changes?
• Have you written new tests for your changes, where applicable?
• Have you successfully run make lint with your changes locally?
• Have you successfully run make test with your changes locally?

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Changes in this Pull Request

Adds a GetLocationAsTimeseries route which returns the capacity values for a given time window.

[github-actions]

Benchmark Results

Benchmark results

?   	github.com/openclimatefix/data-platform/cmd	[no test files]
?   	github.com/openclimatefix/data-platform/internal/gen/ocf/dp	[no test files]
?   	github.com/openclimatefix/data-platform/internal/interceptors	[no test files]
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/dummy	0.005s
{"level":"debug","time":"2026-05-27T12:11:49Z","message":"Completed migrations"}
goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkPostgresClient/small/GetForecastAsTimeseries-4         	      66	  16647527 ns/op
BenchmarkPostgresClient/small/GetForecastAtTimestamp-4          	     271	   4256614 ns/op
BenchmarkPostgresClient/small/GetObservationsAsTimeseries-4     	     912	   1266903 ns/op
BenchmarkPostgresClient/small/CreateForecast-4                  	      90	  12981141 ns/op
BenchmarkPostgresClient/small/StreamForecastData-4              	      10	 104621804 ns/op
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/postgres	71.762s
?   	github.com/openclimatefix/data-platform/internal/server/postgres/gen	[no test files]

Benchmark vs base branch

goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
                                                   │ bench-main.txt │ bench-devsjc-location-as-timeseries.txt │
                                                   │     sec/op     │     sec/op       vs base                │
PostgresClient/small/GetForecastAsTimeseries-4         15.52m ± ∞ ¹      16.65m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/GetForecastAtTimestamp-4          4.133m ± ∞ ¹      4.257m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/GetObservationsAsTimeseries-4     1.267m ± ∞ ¹      1.267m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/CreateForecast-4                  12.92m ± ∞ ¹      12.98m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/StreamForecastData-4              103.0m ± ∞ ¹      104.6m ± ∞ ¹       ~ (p=1.000 n=1) ²
geomean                                                10.16m            10.40m        +2.43%
¹ need >= 6 samples for confidence interval at level 0.95
² need >= 4 samples to detect a difference at alpha level 0.05