migration(grantlee): add patch script to avoid QT_TESTCASE_BUILDDIR redefinition; add Grantlee parser smoke test

app/patches/apply_grantlee_fix.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Apply lightweight fix to Grantlee sources in externals to avoid duplicate
+# QT_TESTCASE_BUILDDIR definition which causes compiler errors on Qt6.
+
+GRANTLEE_SRC_DIR="${1:-./external/grantlee-src}"
+
+if [ ! -d "$GRANTLEE_SRC_DIR" ]; then
+  echo "Grantlee source dir not found: $GRANTLEE_SRC_DIR" >&2
+  exit 2
+fi
+
+TARGET_FILE="$GRANTLEE_SRC_DIR/textdocument/tests/CMakeLists.txt"
+
+if [ ! -f "$TARGET_FILE" ]; then
+  echo "Target CMake file not found: $TARGET_FILE" >&2
+  exit 3
+fi
+
+# Replace the unconditional target_compile_definitions block with a commented
+# explanation to avoid duplicate -D flags.
+
+awk '
+BEGIN{inblock=0}
+/target_compile_definitions\(plainmarkupbuildertest_exec PRIVATE QT_TESTCASE_BUILDDIR/ {inblock=1; print "# QT_TESTCASE_BUILDDIR was previously defined here which could conflict with the"; print "# the definition injected by Qt\'s test configuration. Defining the macro in"; print "# multiple places leads to compiler redefinition errors. The test framework"; print "# already provides this define when needed, so omit the explicit definition"; print "# to avoid duplicate -D flags."; next}
+{ if (inblock) { if (/^endif\(\)/) { inblock=0; next } else next } print }
+' "$TARGET_FILE" > "$TARGET_FILE.tmp" && mv "$TARGET_FILE.tmp" "$TARGET_FILE"
+
+echo "Applied grantlee fix to $TARGET_FILE"