refactor: rename PIP_NO_\* to PIP_HAS_\* with inverted logic

All feature flags now use positive naming (enabled by default):
- PIP_HAS_FILESYSTEM, PIP_HAS_THREADS, PIP_HAS_SOCKET
- PIP_HAS_PROCESS, PIP_HAS_DYNLIB, PIP_HAS_FFT, PIP_HAS_SERIAL

Preprocessor guards inverted:
- #ifndef PIP_NO_X → #ifdef PIP_HAS_X
- #ifdef PIP_NO_X → #ifndef PIP_HAS_X

CMake options default ON instead of OFF.
Platform blocks set flags OFF to disable features.

85 files transformed via Python script + 2 manual fixes.

libs/main/io_devices/pispi.cpp

@@ -43,11 +43,11 @@ REGISTER_DEVICE(PISPI)
 
 
 PISPI::PISPI(const PIString & path, uint speed, PIIODevice::DeviceMode mode): PIIODevice(path, mode) {
-#ifdef PIP_NO_THREADS
+#ifndef PIP_HAS_THREADS
 	setThreadedReadBufferSize(512);
 #else
 	setThreadedReadBufferSize(1024);
-#endif // PIP_NO_THREADS
+#endif // PIP_HAS_THREADS
 	setPath(path);
 	setSpeed(speed);
 	setBits(8);