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>

zshenv

@@ -0,0 +1,25 @@
+# ~/.zshenv - Sourced for ALL shell types (interactive, non-interactive, login, non-login)
+# Keep this file lightweight - it runs for every shell invocation
+
+# Homebrew - Initialize early for all shell types
+eval "$(/opt/homebrew/bin/brew shellenv)"
+
+# Essential PATH entries (needed for all shells including Claude Code)
+export PATH="$HOME/bin:$PATH"
+export PATH="$HOME/.local/bin:$PATH"
+
+# NVM (minimal setup for non-interactive shells)
+export NVM_DIR="$HOME/.nvm"
+if [[ -s "$NVM_DIR/nvm.sh" ]]; then
+  \. "$NVM_DIR/nvm.sh" --no-use 2>/dev/null
+  # Put default node in PATH for non-interactive shells (e.g. Claude Code, scripts)
+  local default_node="$NVM_DIR/alias/default"
+  [[ -r "$default_node" ]] && export PATH="$NVM_DIR/versions/node/$(cat "$default_node")/bin:$PATH"
+fi
+
+# pyenv
+if command -v pyenv 1>/dev/null 2>&1; then
+  export PYENV_ROOT="$HOME/.pyenv"
+  export PATH="$PYENV_ROOT/bin:$PATH"
+  eval "$(pyenv init -)"
+fi