StreamHub: per-signal calibration, config reload, whitespace-tolerant JSON

- Add CalibrationEntry (heap-allocated array[256], char[] fields to stay within
  the 133 MB struct's canonical address limit) plus calibrationMutex_ and
  numCalibration_.
- Implement SetCalibrationEntry/ClearCalibration, BroadcastCalibration,
  BroadcastConfigAck, HandleSetCalibration, HandleReloadConfig.
- Wire setCalibration and reloadConfig into OnWSCommand dispatch.
- Broadcast calibration to each newly connected client after triggerState.
- Fix JSON round-trip bug: replace JsonGetString/JsonGetBool helpers with a
  shared whitespace-tolerant JsonFindValue (tolerates "key" : "value" as
  written by HandleSaveSources); add JsonIsFinite (no <cmath>).
- Extend LoadSourcesFile(bool skipActive) to also parse calibration blocks;
  SourceIsActive checks live sessions before starting a duplicate.
- Extend HandleSaveSources to persist calibration blocks; emit configSaved ack.
- Reload semantics: calibration replaced wholesale, sources added only.

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

Source/Applications/StreamHub/StreamHub.h

@@ -44,6 +44,32 @@ using MARTe::StructuredDataI;
 /** Maximum number of simultaneously connected UDPStreamer sources. */
 static const uint32 kMaxSessions = 32u;
 
+/** Maximum number of stored per-signal calibration entries. */
+static const uint32 kMaxCalibration = 256u;
+
+/** Maximum length of a calibration unit override (mirrors the Go maxUnitLen). */
+static const uint32 kMaxUnitLen = 16u;
+
+/**
+ * @brief One per-signal affine calibration: y = raw*scale + offset.
+ *
+ * Keyed by the source LABEL (not the runtime "sN" id, which is assigned in
+ * add-order and would rebind if the source list were reordered) and by the
+ * BASE signal name (no "[i]" suffix: one entry covers a whole array signal).
+ *
+ * Fixed-size char arrays are used deliberately: embedding 256 StreamString
+ * (each of which allocates its own heap buffer) into a 133 MB struct that is
+ * itself heap-allocated pushes offsets beyond the canonical x86-64 address
+ * limit and causes a SIGSEGV in the constructor.
+ */
+struct CalibrationEntry {
+    char           source[128]; ///< Source label
+    char           signal[128]; ///< Base signal name (no "[i]" suffix)
+    char           unit[17];    ///< Unit override (max kMaxUnitLen chars + NUL)
+    MARTe::float64 scale;
+    MARTe::float64 offset;
+};
+
 /**
  * @brief Top-level StreamHub orchestrator.
  *
@@ -108,6 +134,12 @@ private:
     /** Broadcast {"type":"config","sourceId":...} for one session. */
     void BroadcastConfig(uint32 sessionIdx);
 
+    /** Broadcast {"type":"calibration","cal":[...]} to all clients. */
+    void BroadcastCalibration();
+
+    /** Broadcast {"type":"configSaved"|"configReloaded","ok":...} to all clients. */
+    void BroadcastConfigAck(const char *msgType, bool ok, const char *errText);
+
     /* ---- Trigger (push loop side) ----------------------------------------- */
 
     /**
@@ -146,6 +178,8 @@ private:
     void HandleHistoryInfo(uint32 slotIdx);
     void HandleSetMaxPoints(const char *json);
     void HandlePing(uint32 slotIdx);
+    void HandleSetCalibration(const char *json);
+    void HandleReloadConfig();
 
     /* ---- Binary recorder commands --------------------------------------- */
 
@@ -172,10 +206,29 @@ private:
                            const char *mcGroup, uint16 dataPort);
 
     /**
-     * @brief Load sources from sourcesFile_ (JSON array of
-     * {"label","addr","multicastGroup","dataPort"}) and start them.
+     * @brief Load sources and calibration from sourcesFile_ (a flat JSON array
+     * of {"label","addr","multicastGroup","dataPort"} source blocks and
+     * {"source","signal","scale","offset","unit"} calibration blocks).
+     * @param skipActive when true, a source whose "host:port" is already
+     * streaming is left alone instead of being started a second time.
+     * @return true if the file was read.
      */
-    void LoadSourcesFile();
+    bool LoadSourcesFile(bool skipActive);
+
+    /** @return true if a session for this "host:port" is already active. */
+    bool SourceIsActive(const char *addrPort);
+
+    /**
+     * @brief Store or replace one calibration entry.  An identity entry
+     * (scale 1, offset 0, empty unit) removes any stored one instead.
+     * @return true if the entry was valid (and therefore stored or removed).
+     */
+    bool SetCalibrationEntry(const char *source, const char *signal,
+                             MARTe::float64 scale, MARTe::float64 offset,
+                             const char *unit);
+
+    /** Drop every calibration entry (used by reload, which replaces wholesale). */
+    void ClearCalibration();
 
     /* ---- Tiny JSON helpers ----------------------------------------------- */
 
@@ -220,6 +273,10 @@ private:
     StreamString sourcesFile_; ///< Persistent dynamic source list (JSON)
     uint32  nextSourceId_;   ///< Counter for generated session ids ("sN")
 
+    CalibrationEntry    *calibration_;      ///< Heap-allocated array[kMaxCalibration]
+    uint32              numCalibration_;
+    FastPollingMutexSem calibrationMutex_; ///< Serializes calibration reads/writes
+
     /* Push loop state */
     volatile bool  running_;
     uint32         tickCount_;      ///< incremented each push tick