ci: add shellcheck lint workflow; fix 6 violations

Removes unused drive_width variable (SC2034). Splits local+assign
for emmc_size, host, drive (SC2155). Uses ${var#...} instead of sed
for PCI desc parsing (SC2001). Pipes smartctl through sudo tee to fix
redirect privilege (SC2024).

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

driveAtlas.sh

@@ -410,9 +410,6 @@ generate_10bay_layout() {
     local hostname="$1"
     build_drive_map
 
-    # Fixed width for consistent box drawing (fits device names like "nvme0n1")
-    local drive_width=10
-
     # Box interior width = 136 (determined by 10 bay boxes: 4 + 10*13 + 2)
     # Total box width = 138 (136 interior + 2 for │ borders)
 
@@ -493,7 +490,8 @@ generate_micro_layout() {
 
     # Show eMMC if present
     if [[ -n "$emmc_device" ]]; then
-        local emmc_size=$(lsblk -d -n -o SIZE "/dev/$emmc_device" 2>/dev/null | xargs)
+        local emmc_size
+        emmc_size=$(lsblk -d -n -o SIZE "/dev/$emmc_device" 2>/dev/null | xargs)
         printf "│    ┌─────────────────────────────────────────────────────┐ │\n"
         printf "│    │  Onboard eMMC: %-10s (%s)                  │ │\n" "$emmc_device" "$emmc_size"
         printf "│    └─────────────────────────────────────────────────────┘ │\n"
@@ -689,7 +687,7 @@ get_storage_controllers() {
         [[ -z "$line" ]] && continue
         pci_addr="$(echo "$line" | awk '{print $1}')"
         # Get short description (strip PCI address)
-        desc="$(echo "$line" | sed 's/^[0-9a-f:.]\+ //')"
+        desc="${line#*[0-9a-f:.] }"
         echo "    $pci_addr: $desc"
     done
 }
@@ -709,7 +707,8 @@ get_storage_controllers() {
 #     Values: PCI path strings (for --show-pci option)
 #------------------------------------------------------------------------------
 build_drive_map() {
-    local host="$(hostname | tr -cd '[:alnum:]-_.')"
+    local host
+    host="$(hostname | tr -cd '[:alnum:]-_.')"
     local mapping="${SERVER_MAPPINGS[$host]}"
 
     # Declare global arrays directly
@@ -728,7 +727,8 @@ build_drive_map() {
 
         BAY_TO_PCI_PATH[$slot]="$path"
         if [[ -L "${DISK_BY_PATH}/$path" ]]; then
-            local drive="$(readlink -f "${DISK_BY_PATH}/$path" | sed 's/.*\///')"
+            local drive
+            drive="$(readlink -f "${DISK_BY_PATH}/$path" | sed 's/.*\///')"
             DRIVE_MAP[$slot]="$drive"
             ((mapped_count++))
         else
@@ -1090,7 +1090,7 @@ if [[ "$SKIP_SMART" != true ]]; then
         device="${DRIVE_MAP[$bay]}"
         if [[ -n "$device" && "$device" != "EMPTY" && -b "/dev/$device" ]]; then
             # Launch background job to collect raw smartctl data
-            (sudo smartctl -A -i -H "/dev/$device" > "$SMART_CACHE_DIR/${device}.raw" 2>/dev/null) &
+            (sudo smartctl -A -i -H "/dev/$device" 2>/dev/null | sudo tee "$SMART_CACHE_DIR/${device}.raw" > /dev/null) &
             ((job_count++))
             if ((job_count >= max_parallel_jobs)); then
                 wait -n 2>/dev/null || wait  # wait -n requires bash 4.3+, fall back to wait