refactor(shell): collapse managed tree back into stubs

Drop ~/.config/zsh/{env,interactive,login} modules. PATH and local.zsh
live in .zshenv; interactive UX is a single .zshrc again. Deploy only
installs the three stubs and removes obsolete trees/examples.

.zshenv

@@ -1,20 +1,24 @@
-# easyzsh stub: every zsh loads this. Keep it thin; logic lives under ~/.config/zsh/.
+# Always-on env for every zsh (interactive, login, agents, zsh -c).
 # Machine-local overrides: ~/.config/zsh/local.zsh (never overwritten by deploy).
-EASYZSH_HOME="${XDG_CONFIG_HOME:-$HOME/.config}/zsh"
 
-if [[ -d "$EASYZSH_HOME/env" ]]; then
-  for _easyzsh_f in "$EASYZSH_HOME/env"/*.zsh(N); do
-    # shellcheck disable=SC1090
-    . "$_easyzsh_f"
-  done
-  unset _easyzsh_f
+# Homebrew (macOS). cd /tmp so TCC-protected CWDs do not break brew shellenv.
+if [[ -x /opt/homebrew/bin/brew ]]; then
+  eval "$(cd /tmp && /opt/homebrew/bin/brew shellenv)"
+elif [[ -x /usr/local/bin/brew ]]; then
+  eval "$(cd /tmp && /usr/local/bin/brew shellenv)"
 fi
 
-if [[ -f "$EASYZSH_HOME/local.zsh" ]]; then
+# User-local binaries (pipx, uv tools, grok shim, …).
+# Do not put vendor trees like ~/.grok/bin on PATH wholesale (names like `agent` shadow tools).
+if [[ -d "$HOME/.local/bin" ]]; then
+  case ":${PATH}:" in
+    *":$HOME/.local/bin:"*) ;;
+    *) PATH="$HOME/.local/bin:${PATH}" ;;
+  esac
+  export PATH
+fi
+
+if [[ -f "${XDG_CONFIG_HOME:-$HOME/.config}/zsh/local.zsh" ]]; then
   # shellcheck disable=SC1090
-  . "$EASYZSH_HOME/local.zsh"
-elif [[ -f "$HOME/.config/zshenv.local" ]]; then
-  # Legacy path from earlier easyzsh layouts.
-  # shellcheck disable=SC1090
-  . "$HOME/.config/zshenv.local"
+  . "${XDG_CONFIG_HOME:-$HOME/.config}/zsh/local.zsh"
 fi