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/code/picodeparser.cpp

@@ -153,7 +153,7 @@ bool PICodeParser::isEnum(const PIString & name) {
 }
 
 
-#ifndef PIP_NO_FILESYSTEM
+#ifdef PIP_HAS_FILESYSTEM
 bool PICodeParser::parseFileInternal(const PIString & file, bool follow_includes) {
 	if (proc_files[file]) return true;
 	with_includes = follow_includes;
@@ -179,7 +179,7 @@ bool PICodeParser::parseFileInternal(const PIString & file, bool follow_includes
 	piCout << "parsing" << f.path() << "done";
 	return ret;
 }
-#endif // PIP_NO_FILESYSTEM
+#endif // PIP_HAS_FILESYSTEM
 
 
 void PICodeParser::clear() {