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/console/piterminal.cpp

@@ -23,7 +23,7 @@
 #include "pisharedmemory.h"
 
 #if !defined(PICO_SDK)
-#ifndef PIP_NO_PROCESS
+#ifdef PIP_HAS_PROCESS
 #  ifdef WINDOWS
 #	include <windows.h>
 #	include <wingdi.h>
@@ -979,6 +979,6 @@ bool PITerminal::resize(int cols, int rows) {
 	return ret;
 }
 
-#endif // PIP_NO_PROCESS
+#endif // PIP_HAS_PROCESS
 
 #endif // !PICO_SDK