feat(sql): Speed up LatestForecast, enable pg_cron

[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?

Warning

PRs may be closed if all the above boxes are not checked.

Changes in this Pull Request

A number of speedups/optimizations:

• Updates the forecast table index and LatestForecasts query such that they are used correctly

[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":"2026-01-19T16:45:06Z","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         	     172	   6400149 ns/op
BenchmarkPostgresClient/6144000/GetForecastAtTimestamp-4          	     108	  10788355 ns/op
BenchmarkPostgresClient/6144000/GetObservationsAsTimeseries-4     	     962	   1197873 ns/op
BenchmarkPostgresClient/6144000/CreateForecast-4                  	     276	   4079176 ns/op
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/postgres	184.830s
?   	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-forecast-partitioning.txt │
                                                     │     sec/op     │    sec/op      vs base                 │
PostgresClient/6144000/GetForecastAsTimeseries-4         4.826m ± ∞ ¹    6.400m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/GetForecastAtTimestamp-4         105.00m ± ∞ ¹    10.79m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/GetObservationsAsTimeseries-4     1.307m ± ∞ ¹    1.198m ± ∞ ¹        ~ (p=1.000 n=1) ²
PostgresClient/6144000/CreateForecast-4                  2.612m ± ∞ ¹    4.079m ± ∞ ¹        ~ (p=1.000 n=1) ²
geomean                                                  6.449m          4.286m        -33.54%
¹ need >= 6 samples for confidence interval at level 0.95
² need >= 4 samples to detect a difference at alpha level 0.05