Nix stuff, target optimised static binary builds + rename `conduit_cache_capacity_modifier` to `cache_capacity_modifier`

.github/workflows/ci.yml

@@ -38,8 +38,11 @@ env:
     # Custom nix binary cache if fork is being used
     ATTIC_ENDPOINT: ${{ vars.ATTIC_ENDPOINT }}
     ATTIC_PUBLIC_KEY: ${{ vars.ATTIC_PUBLIC_KEY }}
-    # Get error output from nix that we can actually use
-    NIX_CONFIG: show-trace = true
+    # Get error output from nix that we can actually use, and use our binary caches for the earlier CI steps
+    NIX_CONFIG: |
+      show-trace = true
+      extra-substituters = https://attic.kennel.juneis.dog/conduit https://attic.kennel.juneis.dog/conduwuit https://cache.lix.systems https://conduwuit.cachix.org
+      extra-trusted-public-keys = conduit:eEKoUwlQGDdYmAI/Q/0slVlegqh/QmAvQd7HBSm21Wk= conduwuit:BbycGUgTISsltcmH0qNjFR9dbrQNYgdIAcmViSGoVTE= cache.lix.systems:aBnZUw8zA7H35Cz2RyKFVs3H4PlGTLawyY5KRbvJR8o= conduwuit.cachix.org-1:MFRm6jcnfTf0jSAbmvLfhO3KBMt4px+1xaereWXp8Xg=
 
 permissions:
     packages: write
@@ -115,7 +118,7 @@ jobs:
             - name: Prepare build environment
               run: |
                   echo 'source $HOME/.nix-profile/share/nix-direnv/direnvrc' > "$HOME/.direnvrc"
-                  nix profile install --impure --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
+                  nix profile install --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
                   direnv allow
                   nix develop .#all-features --command true
 
@@ -237,7 +240,7 @@ jobs:
             - name: Prepare build environment
               run: |
                   echo 'source $HOME/.nix-profile/share/nix-direnv/direnvrc' > "$HOME/.direnvrc"
-                  nix profile install --impure --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
+                  nix profile install --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
                   direnv allow
                   nix develop .#all-features --command true