Fix libcurl initialization and cleanup lifecycle

.gitignore

@@ -21,4 +21,7 @@ test_output/
 
 # Test image dumps (defense in depth)
 *.pgm
-*.ppm
+*.ppm
+
+# Generic compiled output
+a.out

src/main.cpp

@@ -18,6 +18,7 @@
 #include <curl/curl.h>
 #include <string>
 #include <thread>
+#include <unistd.h>
 
 namespace {
 
@@ -73,6 +74,7 @@ int main() {
         LOG_ERROR("curl_global_init failed");
         return 1;
     }
+    std::atexit(curl_global_cleanup);
 
     // ---- Load configuration ----
     Config cfg;
@@ -109,6 +111,7 @@ int main() {
     if (!oled.begin(cfg.oledI2CAddr)) {
         LOG_ERROR("Failed to open OLED on I2C bus at 0x"
                   << std::hex << cfg.oledI2CAddr << std::dec);
+        close(lcdFd);
         return 1;
     }
 
@@ -208,6 +211,5 @@ int main() {
         }
     }
 
-    curl_global_cleanup();
     return 0;  // unreachable
-}
+}