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/io_utils/pibroadcast.h

@@ -34,6 +34,7 @@
 //! \~\brief
 //! \~english Multi-channel sender and receiver over multicast, broadcast and loopback endpoints.
 //! \~russian Многоканальный отправитель и приемник через multicast-, broadcast- и loopback-конечные точки.
+#ifndef PIP_NO_SOCKET
 class PIP_IO_UTILS_EXPORT PIBroadcast
 	: public PIThread
 	, public PIEthUtilBase {
@@ -182,5 +183,6 @@ private:
 	int lo_pcnt;
 	bool _started, _send_only, _reinit;
 };
+#endif // PIP_NO_SOCKET
 
 #endif // PIBROADCAST_H