L&D: Templ

[denialanderror]

Swaps out standard Golang templating for Templ. Benefits are as follows:

• Allows templates to be written as Go functions (meaning everything you could do in Go, you can do in a templ function)
• Function parameters are typed (like any Go function) so we have compile time type checking
• Component parameters can be defined alongside the template they relate to
• Only valid HTML can be compiled to a component, so compile time validation
• Easier to unit test without having to use Cypress, which will allow us to properly separate concerns between true E2E testing and component tests
• Simplifies our conditional htmx rendering and handler logic

From my extensive research, this is by far the most popular stack for Golang and htmx. It is a very widely used and well-maintained library with lots of active development. The only real concerns are that it is still fairly young and therefore prone to major changes, though these appear to have been rolled out with decent migration guides to date, and the IDE support isn't great, though better than we have at current with zero type checking or linting.