feat(server): Allow customization of associated point

[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

Modifies the data schema for geometries to contain an associated_point instead of a centroid. This is then used for enclosement calculation. If not set, it defaults to the centroid.

Closes #98.

This is a breaking change to the postgres instance, but since we are not at 1.0.0 release yet, it is not marked as such.

[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	0.004s
{"level":"debug","time":"2025-12-23T00:08:16Z","message":"Running migrations"}
goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkPostgresClient/6144000/GetForecastAsTimeseries-4         	     166	   6848822 ns/op
BenchmarkPostgresClient/6144000/GetForecastAtTimestamp-4          	      44	  24760793 ns/op
BenchmarkPostgresClient/6144000/GetObservationsAsTimeseries-4     	     932	   1216470 ns/op
BenchmarkPostgresClient/6144000/CreateForecast-4                  	     271	   4136853 ns/op
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/postgres	190.021s
?   	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-within-fix.txt      │
                                                     │     sec/op     │    sec/op     vs base                 │
PostgresClient/6144000/GetForecastAsTimeseries-4         4.826m ± ∞ ¹   6.849m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/GetForecastAtTimestamp-4         105.00m ± ∞ ¹   24.76m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/GetObservationsAsTimeseries-4     1.307m ± ∞ ¹   1.216m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/CreateForecast-4                  2.612m ± ∞ ¹   4.137m ± ∞ ¹        ~ (p=1.000 n=1) ²
geomean                                                  6.449m         5.405m        -16.19%
¹ need >= 6 samples for confidence interval at level 0.95
² need >= 4 samples to detect a difference at alpha level 0.05