Initial dotfiles: portable shell configs, Brewfile, and setup guide

Cleaned up for new machine portability: removed hardcoded paths,
EOL packages, and redundant version managers. Consolidated NVM
loading, added work git identity support via includeIf.

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

gitconfig

@@ -0,0 +1,51 @@
+[user]
+	name = Eric Wagoner
+	email = ewagoner@gmail.com
+[credential]
+	helper = osxkeychain
+[mergetool]
+	keepBackup = true
+[filter "media"]
+	required = true
+	clean = git media clean %f
+	smudge = git media smudge %f
+[filter "lfs"]
+	clean = git lfs clean %f
+	smudge = git lfs smudge %f
+	required = true
+[core]
+	excludesfile = ~/.gitignore_global
+[alias]
+	co = checkout
+	ci = commit
+	st = status
+	br = branch
+	hist = log --pretty=format:\"%h %ad | %s%d [%an]\" --graph --date=short
+	type = cat-file -t
+	dump = cat-file -p
+	origin = config remote.origin.url
+	alias = ! git config --get-regexp ^alias\\. | sed -e s/^alias\\.// -e s/\\ /\\ =\\ /
+	ll = log --oneline
+	last = log -1 HEAD --stat
+	cm = commit -m
+	pushh = !git push -u origin $(git rev-parse --abbrev-ref HEAD)
+
+[help]
+	autocorrect = 20
+
+[color]
+	ui = auto
+	diff = auto
+	status = auto
+	branch = auto
+
+[push]
+	default = current
+	autoSetupRemote = true
+
+[diff]
+	colorMoved = zebra
+
+# Use work email for repos under ~/work/
+[includeIf "gitdir:~/work/"]
+	path = ~/.gitconfig-work