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/pifiletransfer.h

@@ -31,7 +31,8 @@
 #include "pibasetransfer.h"
 #include "pidir.h"
 
-#define __PIFILETRANSFER_VERSION 2
+#ifndef PIP_NO_FILESYSTEM
+#  define __PIFILETRANSFER_VERSION 2
 
 
 //! \~\ingroup IO-Utils
@@ -70,7 +71,7 @@ public:
 		PIString dest_path;
 	};
 
-#pragma pack(push, 1)
+#  pragma pack(push, 1)
 
 	//! \~english Custom packet header used by the file-transfer protocol.
 	//! \~russian Пользовательский заголовок пакета, используемый протоколом передачи файлов.
@@ -104,7 +105,7 @@ public:
 			return true;
 		}
 	};
-#pragma pack(pop)
+#  pragma pack(pop)
 
 
 	//! \~english Sends one file-system entry identified by "file".
@@ -262,4 +263,6 @@ inline PICout operator<<(PICout s, const PIFileTransfer::PFTFileInfo & v) {
 	s.restoreControls();
 	return s;
 }
+#endif // PIP_NO_FILESYSTEM
+
 #endif // PIFILETRANSFER_H