feat(flake)!: convert to fs-defined modules

Place all modules in either:
    - `modules/${manager}/${module}.nix`
    - `modules/${manager}/${module}/default.nix`

- `${manager}` - One of `nixos`, `nix-on-droid`, `nix-darwin` or `home-manager`
- `${module}` - Module name (autoimported by configurations, used for exporting)

modules/home-manager/README.md

@@ -0,0 +1,5 @@
+Add your reusable home-manager modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/home-manager/default.nix

@@ -1,10 +0,0 @@
-# Add your reusable home-manager modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  reo101-shell = import ./reo101-shell;
-  reo101-river = import ./reo101-river;
-  reo101-wezterm = import ./reo101-wezterm;
-}

modules/nix-darwin/README.md

@@ -0,0 +1,5 @@
+Add your reusable nix-darwin modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nix-darwin/default.nix

@@ -1,10 +0,0 @@
-# Add your reusable nix-darwin modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  brew = import ./brew;
-  yabai = import ./yabai;
-  system = import ./system;
-}

modules/nix-on-droid/README.md

@@ -0,0 +1,5 @@
+Add your reusable nix-on-droid modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nix-on-droid/default.nix

@@ -1,7 +0,0 @@
-# Add your reusable nix-on-droid modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-}

modules/nixos/README.md

@@ -0,0 +1,5 @@
+Add your reusable NixOS modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nixos/default.nix

@@ -1,8 +0,0 @@
-# Add your reusable NixOS modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  jellyfin = import ./jellyfin.nix;
-}