Ensure live float values always display with a decimal point

Adds _fmt_float() helper that formats 32-bit floats with :.6g precision
but appends .0 when the result has no decimal point, matching Niagara
and .sax file display conventions (e.g. 175.0 not 175, 0.0 not 0).

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

device_session.py

@@ -13,6 +13,14 @@ import schema
 from sox import SoxClient, SoxComponent, TREE, CONFIG, RUNTIME, LINKS, ALL
 
 
+def _fmt_float(val):
+    """Format a 32-bit float for display: 6 significant digits, always with a decimal point."""
+    s = f"{val:.6g}"
+    if "." not in s and "e" not in s and "E" not in s:
+        s += ".0"
+    return s
+
+
 class DeviceSession:
     """High-level session manager for a live Sedona device connection."""
 
@@ -268,7 +276,7 @@ class DeviceSession:
                 if name in sox_comp.values:
                     val = sox_comp.values[name]
                     if isinstance(val, float):
-                        val_str = f"{val:.6g}"
+                        val_str = _fmt_float(val)
                     else:
                         val_str = str(val)
                     ET.SubElement(comp_elem, "prop",
@@ -366,7 +374,7 @@ class DeviceSession:
                 name = slot["name"]
                 if name in sox_comp.values:
                     raw = sox_comp.values[name]
-                    val = f"{raw:.6g}" if isinstance(raw, float) else str(raw)
+                    val = _fmt_float(raw) if isinstance(raw, float) else str(raw)
                     if name in existing_props:
                         existing_props[name].set("val", val)
                     else: