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/piconnection.cpp

@@ -23,7 +23,9 @@
 #include "piiostream.h"
 #include "piliterals_time.h"
 #include "pitime.h"
-#include "pitranslator.h"
+
+#ifndef PIP_NO_THREADS
+#  include "pitranslator.h"
 
 /** \class PIConnection
  * \brief Complex Input/Output point
@@ -1294,3 +1296,5 @@ __DevicePoolContainer__::__DevicePoolContainer__() {
 	inited_         = true;
 	__device_pool__ = new PIConnection::DevicePool();
 }
+
+#endif // PIP_NO_THREADS