Restructure modules/shared and update all imports

- Delete 2024-12-rework/ folder
- Rename modules/hosts/common to modules/shared, then split into:
  - modules/shared/home/general
  - modules/shared/home/linux
  - modules/shared/nixos
- Update all import paths throughout the codebase
- Update lib/*.nix to use new paths
- Fix hardcoded /Users/${username} to use config.home.homeDirectory
- Update README and examples/flake-structure.nix

modules/hosts/common/files/nvim/lua/disabled/barbar.lua

@@ -1,14 +0,0 @@
-return {'romgrk/barbar.nvim',
-  dependencies = {
-    'lewis6991/gitsigns.nvim', -- OPTIONAL: for git status
-    'nvim-tree/nvim-web-devicons', -- OPTIONAL: for file icons
-  },
-  init = function() vim.g.barbar_auto_setup = false end,
-  opts = {
-    -- lazy.nvim will automatically call setup for you. put your options here, anything missing will use the default:
-    -- animation = true,
-    -- insert_at_start = true,
-    -- …etc.
-  },
-}
-