Update stale /sbin/ references to real FHS paths

The reorg moved user binaries under /system (init -> /system/services/init,
drivers -> /system/drivers/<name>, vfs-test -> /system/services/vfs/vfs-test), but
many comments and log strings still named the old /sbin/ home. Retarget them all:
kernel/loader/test comments and the two boot log lines, plus vision.md and the
driver-model.md proposed tree (also dropped the stale `d` suffixes and rt->runtime
there). The initial-ramdisk spawn log no longer fakes a /sbin/ prefix, since those
binaries live in different homes (services vs drivers).

Left the FSH design doc's /sbin and /lib rows alone — whether /sbin stays a
directory at all is a design call for its owner, not a stale-comment fix.

boot/efi.zig

@@ -63,9 +63,9 @@ fn boot() !noreturn {
 
     const entry = try loadKernel(bs, &boot_information);
 
-    // Best effort: a volume without sbin/init still boots (kernel-only).
+    // Best effort: a volume without /system/services/init still boots (kernel-only).
     loadInit(bs, &boot_information) catch |err| {
-        log("danos: no sbin/init (");
+        log("danos: no /system/services/init (");
         logBytes(@errorName(err));
         log(") - booting without user space\r\n");
     };
@@ -389,13 +389,13 @@ fn loadFile(bs: *uefi.tables.BootServices, name: [*:0]const u16) ![]u8 {
     return image[0..size];
 }
 
-/// Ferry the init program (sbin/init) to the kernel. The kernel does the ELF
+/// Ferry the init program (/system/services/init) to the kernel. The kernel does the ELF
 /// loading itself (into ring-3 mappings) — the loader just carries the bytes.
 fn loadInit(bs: *uefi.tables.BootServices, boot_information: *BootInformation) !void {
     const image = try loadFile(bs, init_file_name);
     boot_information.init_base = @intFromPtr(image.ptr);
     boot_information.init_len = image.len;
-    log("danos: sbin/init loaded\r\n");
+    log("danos: /system/services/init loaded\r\n");
 }
 
 /// Ferry the initial_ramdisk (the VFS server + drivers) to the kernel, same as init.