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/pithreadpoolworker.cpp

@@ -1,7 +1,7 @@
 /*
     PIP - Platform Independent Primitives
 
-	Ivan Pelipenko, Stephan Fomenko
+    Ivan Pelipenko, Stephan Fomenko
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as published by
@@ -21,6 +21,8 @@
 
 #include "pisysteminfo.h"
 
+#ifndef PIP_NO_THREADS
+
 //! \addtogroup Thread
 //! \{
 //! \class PIThreadPoolWorker pithreadpoolworker.h
@@ -177,7 +179,7 @@ int64_t PIThreadPoolWorker::enqueueTask(std::function<void(int64_t)> func, PIObj
 						 contexts.remove(context);
 						 auto qref = tasks_queue.getRef();
 						 // auto prev_size = qref->size();
-						 // piCout << "deleted" << (void *)context << qref->map<void *>([](const Task & t) { return t.context; });
+				         // piCout << "deleted" << (void *)context << qref->map<void *>([](const Task & t) { return t.context; });
 						 qref->removeWhere([context](const Task & t) { return t.context == context; });
 						 // piCout << prev_size << qref->size() << qref->map<void *>([](const Task & t) { return t.context; });
 					 }));
@@ -236,3 +238,5 @@ void PIThreadPoolWorker::threadFunc(Worker * w) {
 	taskFinished(task.id);
 	w->notifier.notify();
 }
+
+#endif // PIP_NO_THREADS