Add post letters endpoint #1395

Job	Run time
Set CI/CD metadata	6s
Commit stage / Check file format	6s
Commit stage / Scan secrets	7s
Commit stage / Check Markdown format	8s
Commit stage / Check English usage	10s
Commit stage / Detect Terraform Changes	5s
Commit stage / Count lines of code	8s
Commit stage / Scan dependencies	26s
Commit stage / Check for changes to event schema package compared to main branch	6s
Commit stage / Check TODO usage	4s
Commit stage / Lint Terraform	3s
Commit stage / Run terraform-docs	7s
Commit stage / Trivy Scan	4m 34s
Commit stage / Check event schema version has been updated	0s
Commit stage / Check event schemas have been regenerated	-1s
Test stage / Linting	46s
Test stage / Unit tests	2m 44s
Test stage / Check generated dependencies	47s
Test stage / Typecheck	48s
Test stage / Test coverage	5s
Test stage / Perform static analysis	1m 5s
Acceptance stage	0s
Build stage	0s
Publish stage	0s
	12m 24s

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