Add Maple Mono NF font install to bootstrap

- Arch: paru -S maplemono-nf-cn (AUR package, installed via Chaotic-AUR)
- Debian: download MapleMono-NF.zip from subframe7536/Maple-font v7.9
  release, extract to ~/.local/share/fonts, run fc-cache
- Idempotent: skips if fc-list already shows Maple Mono NF
- Pinned to v7.9 (20.6MB); bump MAPLE_FONT_VERSION when upgrading

Also documented in README that the default Maple Mono NF in nvim
init.lua will Just Work on every box thanks to the bootstrap.

run_once_20-install-user-packages.sh.tmpl

@@ -116,6 +116,40 @@ else
     log "tpm already installed"
 fi
 
+# --------------------------- Maple Mono NF font ----------------------------
+# nvim init.lua references "Maple Mono NF". Install it so the default font works.
+# Pin Maple-font version. Bump manually if a release breaks things.
+MAPLE_FONT_VERSION="v7.9"
+
+if fc-list 2>/dev/null | grep -qi "Maple Mono NF"; then
+    log "Maple Mono NF already installed"
+else
+{{ if eq .os_family "arch" -}}
+    log "installing maplemono-nf-cn from AUR (via paru)"
+    paru -S --needed --noconfirm maplemono-nf-cn
+{{ else if eq .os_family "debian" -}}
+    log "downloading MapleMono-NF.zip from subframe7536/Maple-font $MAPLE_FONT_VERSION"
+    FONT_DIR="$USER_HOME/.local/share/fonts/maple-mono-nf"
+    mkdir -p "$FONT_DIR"
+    TMP_ZIP="$(mktemp /tmp/maple-font.XXXXXX.zip)"
+    if curl -fL --retry 3 \
+        "https://github.com/subframe7536/Maple-font/releases/download/${MAPLE_FONT_VERSION}/MapleMono-NF.zip" \
+        -o "$TMP_ZIP"; then
+        log "extracting font files"
+        unzip -q -o "$TMP_ZIP" -d "$FONT_DIR"
+        rm -f "$TMP_ZIP"
+        log "running fc-cache"
+        fc-cache -fv >/dev/null
+    else
+        log "WARNING: failed to download Maple Mono NF — nvim will warn about missing font"
+        log "manual install: https://github.com/subframe7536/Maple-font"
+        rm -f "$TMP_ZIP"
+    fi
+{{ else -}}
+    log "WARNING: font install not configured for os_family={{ .os_family }}"
+{{ end -}}
+fi
+
 # --------------------------- set zsh as default shell ---------------------
 USER_SHELL="$(getent passwd "$(whoami)" | cut -d: -f7)"
 if [[ "$USER_SHELL" != "$(command -v zsh)" ]]; then