feat(demo): Add --help, fix run_demo.bat path, add iostream to classifier

- Add --help/-h CLI option to demo_offline with usage description
- Fix run_demo.bat validation dataset path: dataset\val -> dataset\binary\val
- Add missing #include <iostream> to gunshot_classifier.cpp for error messages
- All tests pass: test_core_lib 9/9, demo_offline 20/20

src/drone-software/src/acoustic/run_demo.bat

@@ -8,7 +8,7 @@ echo ==========================================
 
 set BUILD_DIR=%~dp0build
 set MODEL=models\gunshot_classifier.onnx
-set VAL_DIR=dataset\val
+set VAL_DIR=dataset\binary\val
 
 REM --- Ensure executables exist ---
 if not exist "%BUILD_DIR%\test_core_lib.exe" (

src/drone-software/src/acoustic/src/core/gunshot_classifier.cpp

@@ -2,6 +2,7 @@
 #include <cmath>
 #include <fstream>
 #include <sstream>
+#include <iostream>
 #include <algorithm>
 #include <numeric>
 #include <memory>

src/drone-software/src/acoustic/tests/demo_offline.cpp

@@ -27,6 +27,9 @@ struct Prediction {
 
 void print_usage(const char* prog) {
     std::cerr << "Usage: " << prog << " <file_or_dir> [--model <onnx>] [--label_map <json>] [--threshold <float>]" << std::endl;
+    std::cerr << "  --model <path>      ONNX model path (default: models/gunshot_classifier.onnx)" << std::endl;
+    std::cerr << "  --label_map <path>  Label map file (default: models/label_map.json)" << std::endl;
+    std::cerr << "  --threshold <float> Detection threshold (default: 0.5)" << std::endl;
 }
 
 bool ends_with(const std::string& s, const std::string& suffix) {
@@ -181,9 +184,9 @@ void print_report(const std::vector<Prediction>& results) {
 }
 
 int main(int argc, char** argv) {
-    if (argc < 2) {
+    if (argc < 2 || std::strcmp(argv[1], "--help") == 0 || std::strcmp(argv[1], "-h") == 0) {
         print_usage(argv[0]);
-        return 1;
+        return argc < 2 ? 1 : 0;
     }
 
     std::string target = argv[1];