fix: add CARGO_HOME/bin to GitHub Actions PATH for rust tests (#749)

* Initial plan

* fix: add CARGO_HOME/bin to GitHub Actions PATH for rust tests

The rust-toolchain action installs rustc/cargo at ~/.cargo/bin but doesn't
add this directory to PATH. This causes "command not found" errors when
running rustc/cargo in chroot mode tests.

Fix by explicitly adding CARGO_HOME/bin to $GITHUB_PATH after detecting
CARGO_HOME from the cargo binary location. This ensures both the host
and the chroot environment can find Rust binaries.

Also added a clarifying comment that CARGO_HOME must be exported so
sudo -E can preserve it for the awf CLI.

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

---------

Co-authored-by: anthropic-code-agent[bot] <242468646+Claude@users.noreply.github.com>
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Claude

.github/workflows/test-chroot.yml

@@ -184,6 +184,7 @@ jobs:
 
           # Rust/Cargo: CARGO_HOME is needed so entrypoint can add $CARGO_HOME/bin to PATH
           # The rust-toolchain action doesn't set CARGO_HOME, so detect it from cargo location
+          # We must export it so sudo -E can preserve it
           if [ -n "$CARGO_HOME" ]; then
             CARGO_HOME_VALUE="$CARGO_HOME"
           else
@@ -199,6 +200,9 @@ jobs:
           fi
           echo "CARGO_HOME=${CARGO_HOME_VALUE}" >> $GITHUB_ENV
           echo "Captured CARGO_HOME: ${CARGO_HOME_VALUE}"
+          # Also add CARGO_HOME/bin to PATH so host's cargo/rustc are accessible
+          echo "${CARGO_HOME_VALUE}/bin" >> $GITHUB_PATH
+          echo "Added CARGO_HOME/bin to PATH"
 
           # Java: JAVA_HOME is needed so entrypoint can add $JAVA_HOME/bin to PATH
           # The setup-java action sets JAVA_HOME but sudo may not preserve it