This is a stripped-down template for 1.92.2 Fabric+Forge Hex Casting addons. It's heavily derived (aka, taken wholesale) from HexCasting's excellent project layout, and was created by stripping everything from Hexal's repository that wasn't relevant.
This has all the dependencies necessary for functioning as an addon, as well as the dependencies and code for a config system that will work for both forge and fabric. There is an example Action, and an example Spell, and you can look at the existing HexCasting or Hexal code to see how actual Actions and Spells are written.
The approach here does not actually avoid the various complexities of cross-modloader programming. You still need to very carefully maintain functions that are distinct between the two environments. It's just a very well-designed approach for separating these fields, without having to duplicate a lot of work.
There will be some follow-up work to turn it from a generic "Hello World" mod into your Generic "Hello World" mod. Some keywords to look at:
yourmod.name.here is the default package name. While valid for test purposes, you will need to change this before release (and ideally immediately after forking) or risk (near-certain) collisions and annoying bugs, and it's easier the earlier you change it.
IntelliJ (and most other IDEAs) will allow bulk refactoring, though expect to need to change a few package settings at the top of files.
See this page for information about package naming rules, particularly don't use a popular TLD that you don't actually own or control.
yourmod is the default modID. AFTER you've refactored your package name, this is the next thing to change. It's only referenced in a few places, but other mods, compile-time behavior (both Forge and Fabric) and maven will interact with it heavily.
See this page for some naming conventions specific to this ID.
After you've made these changes, it's safe to leave YourAPI and YourConfig as their current names, but do feel free to rename them; something specific to your modId or your package will make regularly importing them less obnoxious.
Your Mod is the default mod name. This is more for aesthetics than code relevance, but it does show up in a good few places and it's kinda embarrassing if it's left at default.
Check your mods.toml (for Forge) and fabric.mod.json (for Fabric) regarding other mod-specific settings, such as author, icon, dependencies you want presented to the user, so on. There's a lot I'm not going to summarize here.
Actually Running:
Once you've made those updates, you'll need to reload Gradle. Do it a couple of times, for safety's sake.
The automatically generated Run configurations won't work. Sorry. You'll need to use Gradle->Fabric>Tasks->Fabric->run* or Gradle->Forge->Tasks->forgegradle runs->run*. There's probably a way to fix this, but good luck.