refactor: migrate MICRO_PIP to fine-grained feature flags

Replace monolithic MICRO_PIP/PIP_MICRO with granular flags:

Feature flags (CMake options + platform auto-detection):
- PIP_NO_FILESYSTEM, PIP_NO_THREADS, PIP_NO_SOCKET
- PIP_NO_PROCESS, PIP_NO_DYNLIB, PIP_NO_FFT, PIP_NO_SERIAL

Embedded optimization flag:
- PIP_EMBEDDED (auto-set for Pico SDK and FreeRTOS)
  Controls buffer sizes, time stubs, terminal fallback, init stubs

Platform blocks in CMakeLists.txt:
- Pico SDK: auto-disables FS, PROCESS, DYNLIB, FFT, SERIAL;
  conditionally disables THREADS (no FreeRTOS) and SOCKET (no LWIP)
- FreeRTOS: auto-disables FS, PROCESS, DYNLIB, FFT, SERIAL;
  conditionally disables SOCKET (no LWIP)
- Android: auto-disables PROCESS, DYNLIB, FFT

Updated 96 files across libs/, utils/, tests/, and CMakeLists.txt.
Builds verified for Linux (547 tests pass) and Pico SDK (100%).
Removed all MICRO_PIP and PIP_MICRO references (0 remaining).

libs/main/thread/pithread.h

@@ -44,7 +44,7 @@
 class PIThread;
 
 #ifndef PIP_NO_THREADS
-#ifndef MICRO_PIP
+#  ifndef PIP_NO_THREADS
 class PIIntrospectionThreads;
 
 class PIP_EXPORT __PIThreadCollection: public PIObject {
@@ -75,7 +75,7 @@ public:
 };
 
 static __PIThreadCollection_Initializer__ __PIThreadCollection_initializer__;
-#endif // MICRO_PIP
+#  endif // PIP_NO_THREADS
 
 //! \~english Callback executed by %PIThread with the current \a data() pointer.
 //! \~russian Обратный вызов, который %PIThread выполняет с текущим указателем \a data().
@@ -99,9 +99,9 @@ typedef std::function<void(void *)> ThreadFunc;
 //! проход без повторяющегося цикла обработки очереди.
 class PIP_EXPORT PIThread: public PIObject {
 	PIOBJECT_SUBCLASS(PIThread, PIObject);
-#ifndef MICRO_PIP
+#  ifndef PIP_NO_THREADS
 	friend class PIIntrospectionThreads;
-#endif
+#  endif
 
 public:
 	NO_COPY_CLASS(PIThread);