refactor: remove rec keyword across codebase

Replace rec keyword with modern Nix patterns:
- Use explicit let...in bindings with inherit statements
- Use fix for recursive package bindings in package/default.nix
- This improves maintainability and follows idiomatic Nix patterns

Files modified:
- snowfall-lib/flake/default.nix
- snowfall-lib/fp/default.nix
- snowfall-lib/home/default.nix
- snowfall-lib/system/default.nix
- snowfall-lib/package/default.nix

snowfall-lib/flake/default.nix

@@ -18,8 +18,8 @@ let
     traceVal
     ;
 in
-rec {
-  flake = rec {
+let
+  flake = let
     ## Remove the `self` attribute from an attribute set.
     ## Example Usage:
     ## ```nix
@@ -43,6 +43,8 @@ rec {
     ## ```
     #@ Attrs -> Attrs
     without-src = flake-inputs: builtins.removeAttrs flake-inputs [ "src" ];
+  in {
+    inherit without-self without-src;
 
     ## Remove the `src` and `self` attributes from an attribute set.
     ## Example Usage:
@@ -248,4 +250,7 @@ rec {
           }) (builtins.attrNames flake-outputs.pkgs)
         ));
     };
+in
+{
+  inherit flake mkFlake;
 }

snowfall-lib/fp/default.nix

@@ -9,7 +9,7 @@ let
   inherit (core-inputs.nixpkgs.lib) id foldr flip;
 in
 {
-  fp = rec {
+  fp = let
     ## Compose two functions.
     ## Example Usage:
     ## ```nix
@@ -24,18 +24,6 @@ in
       f: g: x:
       f (g x);
 
-    ## Compose many functions.
-    ## Example Usage:
-    ## ```nix
-    ## compose-all [ add-two add-one ]
-    ## ```
-    ## Result:
-    ## ```nix
-    ## (x: add-two (add-one x))
-    ## ```
-    #@ [(x -> y)] -> a -> b
-    compose-all = foldr compose id;
-
     ## Call a function with an argument.
     ## Example Usage:
     ## ```nix
@@ -47,6 +35,20 @@ in
     ## ```
     #@ (a -> b) -> a -> b
     call = f: x: f x;
+  in {
+    inherit compose call;
+
+    ## Compose many functions.
+    ## Example Usage:
+    ## ```nix
+    ## compose-all [ add-two add-one ]
+    ## ```
+    ## Result:
+    ## ```nix
+    ## (x: add-two (add-one x))
+    ## ```
+    #@ [(x -> y)] -> a -> b
+    compose-all = foldr compose id;
 
     ## Apply an argument to a function.
     ## Example Usage:

snowfall-lib/home/default.nix

@@ -32,7 +32,7 @@ let
   user-modules-root = snowfall-lib.fs.get-snowfall-file "modules";
 in
 {
-  home = rec {
+  home = let
     # Modules in home-manager expect `hm` to be available directly on `lib` itself.
     home-lib =
       # NOTE: This prevents an error during evaluation if the input does
@@ -427,5 +427,14 @@ in
       ++ shared-modules
       ++ shared-user-modules
       ++ system-modules;
+  in {
+    inherit
+      home-lib
+      split-user-and-host
+      create-home
+      get-target-homes-metadata
+      create-homes
+      create-home-system-modules
+      ;
   };
 }

snowfall-lib/package/default.nix

@@ -8,6 +8,7 @@ let
   inherit (core-inputs.flake-utils-plus.lib) filterPackages allSystems;
   inherit (core-inputs.nixpkgs.lib)
     assertMsg
+    fix
     foldl
     mapAttrs
     filterAttrs
@@ -17,7 +18,7 @@ let
   user-packages-root = snowfall-lib.fs.get-snowfall-file "packages";
 in
 {
-  package = rec {
+  package = let
     ## Create flake output packages.
     ## Example Usage:
     ## ```nix
@@ -39,6 +40,15 @@ in
       }:
       let
         user-packages = snowfall-lib.fs.get-default-nix-files-recursive src;
+        merge-packages =
+          packages: metadata:
+          packages
+          // {
+            ${metadata.name} = metadata.drv;
+          };
+        packages-without-aliases = fix (
+          packages-without-aliases:
+          let
             create-package-metadata =
               package:
               let
@@ -56,6 +66,8 @@ in
                   };
               in
               {
+                # We are building flake outputs based on file paths. Nix doesn't allow this
+                # so we have to explicitly discard the string's path context to use it as an attribute name.
                 name = builtins.unsafeDiscardStringContext (snowfall-lib.path.get-parent-directory package);
                 drv =
                   let
@@ -71,14 +83,14 @@ in
                   };
               };
             packages-metadata = builtins.map create-package-metadata user-packages;
-        merge-packages =
-          packages: metadata:
-          packages
-          // {
-            ${metadata.name} = metadata.drv;
-          };
-        packages = snowfall-lib.attrs.merge-with-aliases merge-packages packages-metadata alias // overrides;
+          in
+          foldl merge-packages { } packages-metadata
+        );
+        aliased-items = mapAttrs (name: value: packages-without-aliases.${value}) alias;
+        packages = packages-without-aliases // aliased-items // overrides;
       in
       filterPackages pkgs.stdenv.hostPlatform.system packages;
+  in {
+    inherit create-packages;
   };
 }

snowfall-lib/system/default.nix

@@ -22,7 +22,7 @@ let
   user-modules-root = snowfall-lib.fs.get-snowfall-file "modules";
 in
 {
-  system = rec {
+  system = let
     ## Get the name of a system based on its file path.
     ## Example Usage:
     ## ```nix
@@ -349,5 +349,19 @@ in
         );
       in
       created-systems;
+  in {
+    inherit
+      get-inferred-system-name
+      is-darwin
+      is-linux
+      is-virtual
+      get-virtual-system-type
+      get-target-systems-metadata
+      get-system-builder
+      get-system-output
+      get-resolved-system-target
+      create-system
+      create-systems
+      ;
   };
 }