ci(crow): enable verbose patched builds in the trial-build gate

Set BINCRAFT_VERBOSE_PATCH_BUILD=TRUE so a failed isolated patched build in the
gate prints the real compiler error instead of bincraft's opaque
"System command 'R' failed". Needs bincraft with the flag (codefloe #65);
harmless on older versions.

.crow/trial-build-registry.yaml

@@ -116,6 +116,10 @@ steps:
       ARCH: ${ARCH}
       R_VERSION: ${R_VERSION}
       R_LIBS_USER: /mnt/cache/R-pkgs
+      # Surface the real compiler error when an isolated patched build fails,
+      # instead of bincraft's opaque "System command 'R' failed" (needs bincraft
+      # with BINCRAFT_VERBOSE_PATCH_BUILD support; harmless on older versions).
+      BINCRAFT_VERBOSE_PATCH_BUILD: 'TRUE'
     commands:
       - git clone -q --branch ${patch_branch} https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       - git fetch -q origin main