refactor: reorganize dotfiles into per-platform top-level directories

Group all configs by platform to make the repo easier to navigate and
extend. The flat top-level layout mixed three unrelated setups; this
commit gives each its own directory.

Layout changes:
- omarchy/  ← hypr, waybar, eca, starship, systemd, uwsm, xcompose,
              install.sh (was install_dotfiles_linux.sh)
- macos/    ← zsh, pip, skhd, tmux, yabai, Brewfile,
              install.sh (was install_dotfiles_macos.sh)
- common/   ← doom, authinfo (shared across platforms)
- nixos/    unchanged

Script / config updates:
- omarchy/install.sh: doom stow now uses -d "$SCRIPT_DIR/../common"
- macos/install.sh: add SCRIPT_DIR; all stow calls get explicit -d flags;
  doom and authinfo resolved via common/
- nixos/home/eduardo/default.nix: authinfo out-of-store symlink updated
  to dotfiles/common/authinfo/.authinfo
- Makefile: update install-linux, install-macos, brewfile-update targets

Also add readme.org describing the new layout and installation steps.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: eapolinario

Makefile

@@ -6,7 +6,7 @@ BASELINE := gitleaks.baseline
 # Executable; override if you have gitleaks elsewhere, e.g. `make GITLEAKS=/path/to/gitleaks gitleaks`
 GITLEAKS ?= gitleaks
 
-.PHONY: gitleaks install-linux install-macos gitleaks-baseline-regen brewfile-update
+.PHONY: gitleaks install-linux install-macos gitleaks-baseline-regen brewfile-update help
 # Scan the repository for new secrets. Fails (non-zero exit status) if any leak
 # that is *not* in $(BASELINE) is detected.
 gitleaks:
@@ -16,16 +16,17 @@ gitleaks-baseline-regen:
 	$(GITLEAKS) detect --source . --config .gitleaks.toml --report-format json --report-path $(BASELINE)
 
 install-linux:
-	./install_dotfiles_linux.sh
+	./omarchy/install.sh
 
 install-macos:
-	./install_dotfiles_macos.sh
+	./macos/install.sh
 
 brewfile-update:
-	brew bundle dump --file ./Brewfile --force
+	brew bundle dump --file ./macos/Brewfile --force
 
-.PHONY: help
 help:
 	@echo "Available targets:"
 	@echo "  gitleaks   – Run gitleaks with baseline $(BASELINE)"
+	@echo "  install-linux  – Install dotfiles on Arch Linux / omarchy"
+	@echo "  install-macos  – Install dotfiles on macOS"
 	@echo "  brewfile-update – Update Brewfile from current Homebrew state"

authinfo/.authinfo common/authinfo/.authinfoauthinfo/.authinfo renamed to common/authinfo/.authinfo

@@ -0,0 +1,39 @@
+;;; -*- lexical-binding: t -*-
+(custom-set-variables
+ ;; custom-set-variables was added by Custom.
+ ;; If you edit it by hand, you could mess it up, so be careful.
+ ;; Your init file should contain only one such instance.
+ ;; If there is more than one, they won't work right.
+ '(custom-safe-themes
+   '("7771c8496c10162220af0ca7b7e61459cb42d18c35ce272a63461c0fc1336015"
+     "0f1341c0096825b1e5d8f2ed90996025a0d013a0978677956a9e61408fcd2c77"
+     "a368631abdadffb6882f9994637d7216167912311447f1ec02f9dc58e9cc62a9"
+     "9d5124bef86c2348d7d4774ca384ae7b6027ff7f6eb3c401378e298ce605f83a"
+     "e4d4cc443964b8a64defc06de3edb2363f7cb1b3c3ae2272b2c1487f626e4318"
+     "d12b1d9b0498280f60e5ec92e5ecec4b5db5370d05e787bc7cc49eae6fb07bc0"
+     "7de64ff2bb2f94d7679a7e9019e23c3bf1a6a04ba54341c36e7cf2d2e56e2bcc"
+     "f1e8339b04aef8f145dd4782d03499d9d716fdc0361319411ac2efc603249326"
+     "21d2bf8d4d1df4859ff94422b5e41f6f2eeff14dd12f01428fa3cb4cb50ea0fb"
+     "d97ac0baa0b67be4f7523795621ea5096939a47e8b46378f79e78846e0e4ad3d"
+     "19d62171e83f2d4d6f7c31fc0a6f437e8cec4543234f0548bad5d49be8e344cd"
+     "b7a09eb77a1e9b98cafba8ef1bd58871f91958538f6671b22976ea38c2580755"
+     "0c83e0b50946e39e237769ad368a08f2cd1c854ccbcd1a01d39fdce4d6f86478"
+     "f253a920e076213277eb4cbbdf3ef2062e018016018a941df6931b995c6ff6f6"
+     "b5fd9c7429d52190235f2383e47d340d7ff769f141cd8f9e7a4629a81abc6b19"
+     "3f24dd8f542f4aa8186a41d5770eb383f446d7228cd7a3413b9f5e0ec0d5f3c0"
+     "fd22a3aac273624858a4184079b7134fb4e97104d1627cb2b488821be765ff17"
+     "e4a702e262c3e3501dfe25091621fe12cd63c7845221687e36a79e17cf3a67e0" default))
+ '(elfeed-feeds
+   '("https://feeds.bbci.co.uk/news/rss.xml"
+     "https://this-week-in-rust.org/rss.xml"
+     ("http://feeds.bbci.co.uk/news/rss.xml" news tops)
+     ("https://this-week-in-rust.org/rss.xml" programming rust))))
+(custom-set-faces
+ ;; custom-set-faces was added by Custom.
+ ;; If you edit it by hand, you could mess it up, so be careful.
+ ;; Your init file should contain only one such instance.
+ ;; If there is more than one, they won't work right.
+ '(evil-ex-lazy-highlight ((t nil)))
+ '(lazy-highlight ((t (:background "gainsboro" :foreground "dark slate gray"))))
+ '(org-todo ((t nil))))
+(put 'narrow-to-region 'disabled nil)