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/m4/reallocarray.m4

@@ -0,0 +1,35 @@
+# reallocarray.m4
+# serial 7
+dnl Copyright (C) 2017-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN([gl_FUNC_REALLOCARRAY],
+[
+  dnl Persuade glibc <stdlib.h> to declare reallocarray.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_CHECK_MALLOC_PTRDIFF])
+  AC_REQUIRE([gl_FUNC_REALLOC_0_NONNULL])
+  gl_CHECK_FUNCS_ANDROID([reallocarray], [[#include <stdlib.h>]])
+  if test "$ac_cv_func_reallocarray" = no; then
+    HAVE_REALLOCARRAY=0
+    case "$gl_cv_onwards_func_reallocarray" in
+      future*) REPLACE_REALLOCARRAY=1 ;;
+    esac
+  else
+    if test "$gl_cv_malloc_ptrdiff" = no; then
+      REPLACE_REALLOCARRAY=1
+    fi
+    case "$gl_cv_func_realloc_0_nonnull" in
+      *yes) ;;
+      *) REPLACE_REALLOCARRAY=1 ;;
+    esac
+  fi
+])
+
+# Prerequisites of lib/reallocarray.c.
+AC_DEFUN([gl_PREREQ_REALLOCARRAY], [:])