fix(test/ci): compile the library tests in release mode, and keep them compiling

`Node::debug_assert_peer_maps_coherent` exists only under
`#[cfg(debug_assertions)]`, and the handshake-presence test called it
without that gate, so `cargo test --release --lib` failed to build with
E0599 while every sibling call site was gated correctly. Gate the call
rather than the whole test, so the rest of its assertions still run under
`--release`.

Nothing noticed, because no runner ever compiled the test target with
optimisations: local CI builds release binaries but tests in debug, and
the GitHub unit-test job does the same. Add `cargo test --release --lib
--no-run` to both runners so the next debug-only helper used without its
gate fails at once instead of waiting for someone to run the suite in
release.

.github/workflows/ci.yml

@@ -330,6 +330,14 @@ jobs:
       - name: Run library tests with the tick-body profiler enabled
         run: cargo test --lib --features profiling
 
+      # Debug-only helpers (anything behind #[cfg(debug_assertions)]) vanish in
+      # a release build, so a test calling one without the same gate breaks a
+      # build no other job performs: every run above compiles the test target
+      # in debug. Compile it in release too, without running it — the point is
+      # that it builds at all. Mirrored in testing/ci-local.sh.
+      - name: Compile the library tests in release mode
+        run: cargo test --release --lib --no-run
+
 # ─────────────────────────────────────────────────────────────────────────────
 # Job 2b – Unit tests (macOS)
 # ─────────────────────────────────────────────────────────────────────────────

src/node/tests/unit.rs

@@ -3977,7 +3977,10 @@ fn handshake_presence_tracks_the_carrier_not_the_noise_handles() {
             "rekey-msg2 discriminator: {when}"
         );
         // Fires the live-carrier coherence assertion; a machine that had gone
-        // invisible would panic here rather than fail an assert_eq above.
+        // invisible would panic here rather than fail an assert_eq above. The
+        // helper only exists in debug builds, so the rest of this test carries
+        // on without it under `--release`.
+        #[cfg(debug_assertions)]
         node.debug_assert_peer_maps_coherent();
     };
 

testing/ci-local.sh

@@ -603,6 +603,20 @@ run_tests() {
     else
         record "unit-tests-profiling" 1
     fi
+
+    # Debug-only helpers (anything behind #[cfg(debug_assertions)]) vanish in a
+    # release build, so a test calling one without the same gate breaks a build
+    # nothing here ever performs: every run above compiles the test target in
+    # debug. Compile it in release too, without running it — the point is that
+    # it builds at all. Mirrored in .github/workflows/ci.yml; check-ci-parity.sh
+    # compares integration suites only and would not catch a stage added to one
+    # runner and not the other.
+    info "cargo test --release --lib --no-run"
+    if cargo test --release --lib --no-run 2>&1; then
+        record "release-test-compile" 0
+    else
+        record "release-test-compile" 1
+    fi
 }
 
 # ── Stage 3: Integration Tests ─────────────────────────────────────────────