BETA VERSIONS!  Two options, see below.

Requires ALL THREE major DLC (Automatron, Far Harbor, and Nuka World).  The workshops are not required.

It is HIGHLY RECOMMENDED that you use a mod that changes loot lists to reduce the ammo found in containers, such as Less Loot and Ammo.

This mod works great with my Faster Swords and Melee Rebalance mod.  It also works great with any standalone weapon mods that put their weapons into the leveled lists, such as Crossbows of the Commonwealth.  Given the number of standalone weapon mods on the Nexus, you could probably create a world with exactly the types and number of weapons you want using this mod as the base.  Go nuts!

What it does:
Rather than change the leveled equipment lists, this mod changes which enemies spawn with what lists, giving the vast majority of them melee weapons.  It greatly increases the price of ammunition and explosives (x5-x10) as well.  Enemies no longer have infinite grenades, and use them up when thrown.  Laser turrets have infinite ammo, but machinegun turrets don't, and run out quickly, same for robot weapons.  Companions no longer have their ranged weapons with infinite ammo.  Weapons that use "improvised" ammo, such as the Railway Rifle, Broadsider, and Harpoon Gun, are unaffected.  It also removes combat shotguns from the game because they're unbalanced with this mod.  Suiciders will not detonate their mini-nukes for the same reason.  Instead, they attack unarmed unless they've picked up a weapon.

There are two versions of this mod.  The "optional" file only does those things mentioned above.  The main file is the full version, which not only changes the NPC inventories and ammo prices, but also makes it so all weapons have the "NPCs use ammo" box ticked, so enemies and NPCs can easily run out if not killed quickly.  The top-level turrets (Mk VII) are removed from lists and cannot spawn, and all in-world frag mines are gone. 

What's left:
Named NPCs, DC guards, and random non-hostile NPCs still have their guns.  BOS troops still have their lasers, as well.  In the full version, they have very limited ammo, however.

Known Bug:
Frag Mines sometimes still appear in-world.  They can explode and be disarmed, but disappear once in your inventory.  If one explodes or is disarmed, but then you load a save from before it exploded or was disarmed, it will be gone upon revisiting the location, but if you exit and return to the game, then visit the location again, it will be back.  This may be caused by a conflict in my own load order, but I've been unable to isolate or resolve it, so it's pretty much going to stay in if you experience it.  The mod still removes the majority of mines, but seems to remove fewer and fewer as you go south.

Future Plans:
This is very close to my final version, but I do plan to make the bowling-ball launcher mod for the Fat Man available without even going to Far Harbor.  The Striker will still be a superior version of it, of course.

Old alpha version:
This version just deletes all weapons and ammo from the leveled and loot lists FOR THE CORE GAME ONLY, and can be used as a base for adding your own guns using other mods, so I've left it up.
It has a known issue with Dogmeat, see comments for details and workaround.
Note that replacers won't work with the alpha version, as the originals are removed from the game, so there is nothing to replace.  You have to use standalone weapons that add themselves to the leveled lists.

Want more melee weapons?  Get my Hewing Spear and Battleaxe mods.