fix: improve shell detection, curl flags, and cleanup robustness

- Use ZSH_VERSION instead of ZSH_NAME for reliable zsh detection
- Document NVIM_* env vars as optional external overrides
- Add -fsSL flags to curl for mise bootstrap
- Consolidate duplicate shellcheck directives in install-fonts.sh
- Add explicit return 0 to cleanup script helper functions
- Add actionable remediation to uv-not-found error message

config/exports

@@ -347,7 +347,8 @@ export AWS_CONFIGURE_SESSION_MFA=true
 msg "Setting up Mason configuration"
 export MASON_HOME="$XDG_DATA_HOME/nvim/mason"
 
-# Neovim environment variables
+# Neovim environment variables — optional overrides for external tools.
+# Neovim itself uses vim.fn.stdpath() and does not read these.
 msg "Setting up Neovim configuration"
 [ -z "${NVIM_STATE:-}" ] && export NVIM_STATE="$XDG_STATE_HOME/nvim"
 [ -z "${NVIM_CONFIG_HOME:-}" ] && export NVIM_CONFIG_HOME="$XDG_CONFIG_HOME/nvim"
@@ -503,7 +504,7 @@ export SQLITE_HISTORY="${XDG_CACHE_HOME}/sqlite_history"
 # mise — unified tool version manager
 # https://mise.jdx.dev
 if command -v mise &> /dev/null; then
-  if [ -n "${ZSH_NAME:-}" ]; then
+  if [ -n "${ZSH_VERSION:-}" ]; then
     eval "$(mise activate zsh)"
   else
     eval "$(mise activate bash)"