fix(fuzzing): CFL image belongs at .clusterfuzzlite/Dockerfile (correction to #127)

.clusterfuzzlite/Dockerfile

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: MPL-2.0
+# ClusterFuzzLite build image for rpa-elysium (language: rust).
+#
+# Per ClusterFuzzLite's build-integration docs, this file MUST be named
+# `Dockerfile` inside `.clusterfuzzlite/` — the build action looks for
+# exactly that path. The repo previously shipped the same content as
+# `.clusterfuzzlite/Containerfile`, which the action never reads; every
+# fuzz run failed with "failed to read dockerfile: open Dockerfile: no
+# such file or directory".
+FROM gcr.io/oss-fuzz-base/base-builder-rust
+
+RUN apt-get update && apt-get install -y make autoconf automake libtool
+
+# base-builder-rust ships the pinned nightly toolchain and cargo-fuzz
+# pre-installed (see CFL docs, "Integrating a Rust project"); nothing
+# else to install for this project.
+
+COPY . $SRC/project
+WORKDIR $SRC/project
+
+COPY .clusterfuzzlite/build.sh $SRC/

.clusterfuzzlite/build.sh

@@ -8,7 +8,7 @@
 #   'nightly' is not installed".
 # * $SANITIZER is exported by ClusterFuzzLite (address | undefined) and must
 #   be forwarded so each matrix build instruments for its own sanitizer.
-# * cargo-fuzz is installed by the root Dockerfile.
+# * cargo-fuzz ships pre-installed in base-builder-rust (CFL rust docs).
 cd "$SRC/project"
 cargo fuzz build --release --sanitizer "$SANITIZER"
 # Copy only the fuzz binary — the `fuzz_*` glob also matched .d files.