with compiling very strict standard compiance, remove warings with include_next (GNU extension)

platformio.ini

@@ -25,6 +25,7 @@ build_flags =
     -D CCACHE_ENABLE=1
     -Wno-error=pedantic
     -Wno-pedantic
+    -Wno-gnu-include-next
 
 ; --- STRICT MODE FOR MY OWN CODE ONLY ---
 ; These flags are strictly applied ONLY to files inside the src/ directory.
@@ -37,6 +38,7 @@ build_src_flags =
     -Wconversion      ; Warns on implicit type conversions (e.g., int to uint8_t)
     -Wshadow          ; Warns if a local variable shadows another variable in scope
     -Werror           ; Promotes all warnings to hard compilation errors to guarantee clean code
+    -Wno-gnu-include-next   ; no warning to #include_next (GNU extension), used in static_assert()
 
 ; Serial flashing interface configuration overrides (leave commented out for dynamic CLI arguments)
 ; upload_port = /dev/ttyUSB0