boot: fix ramdisk paths lost to FAT name uppercasing; widen driver-name buffers

The EFI loader now ENUMERATES /system rather than opening files by name,
so the on-disk name must be exact, not merely case-insensitively
findable. make-fat-image.py stored 8.3-fitting lowercase names as bare
uppercase short entries ('init' -> INIT), garbling the ramdisk paths;
now any name whose case the 8.3 entry cannot reproduce gets a long-name
chain carrying the exact name.

device-manager's driver table stored names in 24 bytes — silently
truncating '/system/drivers/usb-xhci-bus' and failing the spawn; widen
to 64 (= abi.maximum_process_name). The usb-report harness regex learns
that restart lines name drivers by path.

tools/make-fat-image.py

@@ -179,14 +179,17 @@ def short_name_for(name, used):
     else:
         base, ext = name, ""
     upper_base, upper_ext = base.upper(), ext.upper()
-    # A name fits 8.3 if it is short enough and uses valid characters; a lowercase
-    # name is simply stored uppercased (FAT is case-insensitive, so the bootloader
-    # and the danos driver still find it). Only genuinely non-8.3 names (too long,
-    # e.g. initial-ramdisk.img) get a mangled short name plus LFN entries.
+    # A name fits 8.3 if it is short enough and uses valid characters. The raw
+    # 8.3 entry is always uppercase; if that loses the real name's case (e.g.
+    # "init" -> "INIT"), a long-name chain carries the exact name. This matters
+    # because the EFI loader *enumerates* /system to build the ramdisk — it gets
+    # back whatever the directory stores, so the stored name must be exact, not
+    # merely case-insensitively findable.
     fits = (1 <= len(base) <= 8 and len(ext) <= 3
             and all(c in VALID_83 for c in upper_base + upper_ext))
     if fits:
-        return (upper_base.ljust(8) + upper_ext.ljust(3)).encode("ascii"), False
+        exact = base == upper_base and ext == upper_ext
+        return (upper_base.ljust(8) + upper_ext.ljust(3)).encode("ascii"), not exact
     # Mangle to STEM~N.EXT.
     stem = "".join(c for c in upper_base if c in VALID_83 and c != " ")[:6] or "FILE"
     index = 1