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/tests/diff3

@@ -3,18 +3,6 @@
 
 . "${srcdir=.}/init.sh"; path_prepend_ ../src
 
-# Some systems lack seq.
-# A limited replacement for seq: handle 1 or 2 args; increment must be 1
-seq()
-{
-  case $# in
-    1) start=1  final=$1;;
-    2) start=$1 final=$2;;
-    *) echo you lose 1>&2; exit 1;;
-  esac
-  awk 'BEGIN{for(i='$start';i<='$final';i++) print i}' < /dev/null
-}
-
 echo a > a || framework_failure_
 echo b > b || framework_failure_
 echo c > c || framework_failure_
@@ -30,12 +18,14 @@ EOF
 
 fail=0
 
-diff3 a b c > out 2> err || fail=1
+# Use --diff-program=diff since --program-transform-name and similar are
+# applied after 'make install'.
+diff3 --diff-program=diff a b c > out 2> err || fail=1
 compare exp out || fail=1
 compare /dev/null err || fail=1
 
 # Repeat, but with all three files the same:
-diff3 a a a > out 2> err || fail=1
+diff3 --diff-program=diff a a a > out 2> err || fail=1
 compare /dev/null out || fail=1
 compare /dev/null err || fail=1
 
@@ -101,7 +91,7 @@ cat <<'EOF' > exp40 || framework_failure_
   3z
 EOF
 
-diff3 d e f > out 2> err
+diff3 --diff-program=diff d e f > out 2> err
 compare exp40 out || fail=1
 compare /dev/null err || fail=1