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/piethernet.h

@@ -29,7 +29,7 @@
 #include "piiodevice.h"
 #include "pinetworkaddress.h"
 
-#ifndef PIP_NO_SOCKET
+#ifdef PIP_HAS_SOCKET
 
 #  ifdef ANDROID
 struct
@@ -706,5 +706,5 @@ inline bool operator!=(const PIEthernet::Interface & v0, const PIEthernet::Inter
 	return (v0.name != v1.name || v0.address != v1.address || v0.netmask != v1.netmask);
 }
 
-#endif // PIP_NO_SOCKET
+#endif // PIP_HAS_SOCKET
 #endif // PIETHERNET_H