feat(tcp): TCPStreamer DataSources, in-process TCPStreamService, stream multiplexing and TCPStreamJoin

Add TCPStreamer/TCPStreamerClient (TCP transport behind the UDPSServerI/UDPSClientI
seam), an optional single in-process TCPStreamService serving many streams over
worker threads, multiplexed SUBSCRIBE (comma list, stream index in fragmentIdx),
and TCPStreamJoin, which merges several streams into one sample-and-hold stream
paced by a master. StreamHub takes a comma list of streams over one connection.
Includes GTests, E2E scenarios s58-s73 and docs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Source/Components/Interfaces/TCPStreamService/TCPSWorker.h

@@ -0,0 +1,68 @@
+#ifndef TCPS_WORKER_H_
+#define TCPS_WORKER_H_
+
+/**
+ * @file TCPSWorker.h
+ * @brief One I/O thread of a TCPStreamService (internal).
+ *
+ * Owns a set of connections, polls them (plus a self-pipe used by producers to
+ * announce new frames), performs the SUBSCRIBE handshake, flushes the bounded
+ * queues and evicts stalled / dead peers.
+ */
+
+#include "EmbeddedServiceMethodBinderI.h"
+#include "ExecutionInfo.h"
+#include "FastPollingMutexSem.h"
+#include "SingleThreadService.h"
+
+#include <poll.h>
+
+namespace MARTe {
+
+class TCPStreamService;
+struct TCPSConn;
+
+class TCPSWorker : public EmbeddedServiceMethodBinderI {
+public:
+    TCPSWorker(TCPStreamService &owner, uint32 maxConns);
+    virtual ~TCPSWorker();
+
+    bool Start(uint32 cpuMask, uint32 stackSize);
+    void Stop();
+
+    /** Hand a freshly accepted connection to this worker (acceptor thread). */
+    bool AddIncoming(TCPSConn *c);
+    /** Interrupt the poll so queued data is flushed now (any thread, cheap). */
+    void Wake();
+    /** @return connections currently assigned (approximate). */
+    int32 Load() const;
+
+    virtual ErrorManagement::ErrorType Execute(ExecutionInfo &info);
+
+private:
+    void AdoptIncoming();
+    bool HandshakeStep(TCPSConn &c);
+    bool Drain(TCPSConn &c);
+    void CloseConn(TCPSConn *c);
+    void CloseAll();
+
+    TCPStreamService &service;
+    uint32 maxConns;
+
+    SingleThreadService thread;
+    int wakeFd[2];
+
+    FastPollingMutexSem incomingMutex;
+    TCPSConn **incoming;
+    uint32 numIncoming;
+
+    TCPSConn **conns;
+    uint32 numConns;
+    struct pollfd *pfds;
+
+    volatile int32 load;
+};
+
+} // namespace MARTe
+
+#endif // TCPS_WORKER_H_