fix: resolve LABEL= syntax for RPi data partition

The cmdline uses kubesolo.data=LABEL=KSOLODATA, but the wait loop
in 20-persistent-mount.sh checked [ -b "LABEL=KSOLODATA" ] which
is always false — it's a label reference, not a block device path.

Fix by detecting LABEL= prefix and resolving it to a block device
path via blkid -L in the wait loop. Also loads mmc_block module as
fallback for platforms where it's not built-in.

Adds debug output listing available block devices on failure.

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

init/lib/20-persistent-mount.sh

@@ -11,28 +11,58 @@ fi
 # Load block device drivers before waiting (modules loaded later in stage 30,
 # but we need virtio_blk available NOW for /dev/vda detection)
 modprobe virtio_blk 2>/dev/null || true
+modprobe mmc_block 2>/dev/null || true
 # Trigger mdev to create device nodes after loading driver
 mdev -s 2>/dev/null || true
 
-# Fallback: create device node from sysfs if devtmpfs/mdev didn't
-DEV_NAME="${KUBESOLO_DATA_DEV##*/}"
-if [ ! -b "$KUBESOLO_DATA_DEV" ] && [ -f "/sys/class/block/$DEV_NAME/dev" ]; then
+# Resolve LABEL= syntax to actual block device path
+# The RPi cmdline uses kubesolo.data=LABEL=KSOLODATA which needs resolution
+WAIT_SECS=30
+log "Waiting for data device: $KUBESOLO_DATA_DEV"
+
+case "$KUBESOLO_DATA_DEV" in
+    LABEL=*)
+        # Extract label name and resolve via blkid/findfs
+        DATA_LABEL="${KUBESOLO_DATA_DEV#LABEL=}"
+        RESOLVED=""
+        for i in $(seq 1 "$WAIT_SECS"); do
+            mdev -s 2>/dev/null || true
+            RESOLVED=$(blkid -L "$DATA_LABEL" 2>/dev/null) || true
+            if [ -z "$RESOLVED" ]; then
+                RESOLVED=$(findfs "LABEL=$DATA_LABEL" 2>/dev/null) || true
+            fi
+            if [ -n "$RESOLVED" ] && [ -b "$RESOLVED" ]; then
+                log "Resolved LABEL=$DATA_LABEL -> $RESOLVED"
+                KUBESOLO_DATA_DEV="$RESOLVED"
+                break
+            fi
+            sleep 1
+        done
+        ;;
+    *)
+        # Direct block device path — wait for it to appear
+        # Fallback: create device node from sysfs if devtmpfs/mdev didn't
+        DEV_NAME="${KUBESOLO_DATA_DEV##*/}"
+        if [ ! -b "$KUBESOLO_DATA_DEV" ] && [ -f "/sys/class/block/$DEV_NAME/dev" ]; then
             MAJMIN=$(cat "/sys/class/block/$DEV_NAME/dev")
             mknod "$KUBESOLO_DATA_DEV" b "${MAJMIN%%:*}" "${MAJMIN##*:}" 2>/dev/null || true
             log "Created $KUBESOLO_DATA_DEV via mknod ($MAJMIN)"
-fi
-
-# Wait for device to appear (USB, slow disks, virtio)
-log "Waiting for data device: $KUBESOLO_DATA_DEV"
-WAIT_SECS=30
-for i in $(seq 1 "$WAIT_SECS"); do
+        fi
+        for i in $(seq 1 "$WAIT_SECS"); do
             [ -b "$KUBESOLO_DATA_DEV" ] && break
             mdev -s 2>/dev/null || true
             sleep 1
-done
+        done
+        ;;
+esac
 
 if [ ! -b "$KUBESOLO_DATA_DEV" ]; then
     log_err "Data device $KUBESOLO_DATA_DEV not found after ${WAIT_SECS}s"
+    # Show available block devices for debugging
+    log_err "Available block devices:"
+    ls -la /dev/mmc* /dev/sd* /dev/vd* 2>/dev/null | while read -r line; do
+        log_err "  $line"
+    done
     return 1
 fi