bootloader: rebase onto upstream 1.0.0, sync firmware-loader version

Bootloader fork rebase:
- Base changed from 0.1.0 pre-patched archive to upstream 1.0.0 tag (c7eeb9f)
- Applied 0001-redbear-local-forks.patch (Cargo.toml crate path redirects)
- Applied fix-uefi-alloc-panic.patch equivalents (4 panic!() -> graceful
  error handling in src/main.rs)
- Applied P5-live-preload-cap-1gib.patch (1 GiB cap on live image preload)
- Skipped: P0 GPT partition scan (requires new module + integration),
  P1 timeout/default-resolution, P2 live preload guard (subsumed by
  panic fixes + cap), P3 live image safe read, P4 large ISO boot,
  redox.patch — to be applied in dedicated rebase session.

firmware-loader/Cargo.toml: version 0.1.0 -> 0.3.0 (sync with other
Red Bear custom crates which are at 0.3.0).

fork-upstream-map.toml: bootloader back from PENDING_REBASE to 1.0.0
since the partial rebase matches upstream 1.0.0 content.

fork-upstream-map.toml: base restored to 'main' tracked (was correctly
tracked by build-redbear.sh).

local/recipes/tools/diffutils/source/lib/reallocarray.c

@@ -0,0 +1,38 @@
+/* reallocarray function that is glibc compatible.
+
+   Copyright (C) 2017-2025 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* written by Darshit Shah */
+
+#include <config.h>
+
+#include <stdckdint.h>
+#include <stdlib.h>
+#include <errno.h>
+
+void *
+reallocarray (void *ptr, size_t nmemb, size_t size)
+{
+  size_t nbytes;
+  if (ckd_mul (&nbytes, nmemb, size))
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+
+  /* Call realloc, setting errno to ENOMEM on failure.  */
+  return realloc (ptr, nbytes);
+}