fix: bundle partprobe in initramfs + robust partition re-read

partprobe was never in initramfs — all partition table re-reads
after sfdisk were silently failing, causing mkfs.vfat to fail on
NVMe because /dev/nvme0n1p1 didn't exist yet.

Now: partprobe bundled, plus blockdev/busybox/sfdisk --verify as
fallbacks, with 5s polling loop for device node appearance.

Co-Authored-By: Claude Opus 4.6 (1M context) <[e-mail]>

fedac/native/docker-build.sh

···
 done
 
 # ── 2i2: Disk/EFI tools (for HD install + OTA flash) ──
-for tool in sfdisk mkfs.vfat efibootmgr; do
+for tool in sfdisk mkfs.vfat efibootmgr partprobe; do
     SRC_BIN=$(command -v "$tool" 2>/dev/null)
     if [ -n "$SRC_BIN" ]; then
         cp -L "$SRC_BIN" "$IROOT/bin/"

fedac/native/src/ac-native.c

···
                     snprintf(rcmd, sizeof(rcmd), "partprobe /dev/%s 2>&1 || blockdev --rereadpt /dev/%s 2>&1",
                              parent_blk, parent_blk);
                     system(rcmd);
+                    // Force kernel to re-read partition table (multiple methods)
+                    snprintf(rcmd, sizeof(rcmd),
+                        "partprobe /dev/%s 2>/dev/null; "
+                        "blockdev --rereadpt /dev/%s 2>/dev/null; "
+                        "busybox blockdev --rereadpt /dev/%s 2>/dev/null; "
+                        "sfdisk --verify /dev/%s 2>/dev/null",
+                        parent_blk, parent_blk, parent_blk, parent_blk);
+                    system(rcmd);
                     // Wait for partition device node to appear (up to 5s)
                     for (int wait = 0; wait < 10; wait++) {
                         usleep(500000);
···
                             break;
                         }
                         ac_log("[install] waiting for %s... (%d)\n", devpath, wait);
-                        // Re-probe each iteration
-                        snprintf(rcmd, sizeof(rcmd), "partprobe /dev/%s 2>/dev/null", parent_blk);
-                        system(rcmd);
                     }
                     // Reformat
                     snprintf(rcmd, sizeof(rcmd), "mkfs.vfat -F 32 -n AC-NATIVE %s 2>&1", devpath);