data_model: implement range_at_100 procedural field

Compute estimated full-charge range from totalRange and current SOC.
Guard against None values (_get returns None for missing keys) and
SOC = 0 to avoid TypeError / ZeroDivisionError on incomplete records.

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

server/data_model.py

@@ -265,6 +265,11 @@ def apply_procedural(record: dict) -> dict:
     """
     proc: dict = {}
 
+    range_at_soc = _get(record, "measurements", "rangeStatus", "totalRange", "value")
+    soc          = _get(record, "charging",      "batteryStatus", "currentSOC", "value")
+    if range_at_soc is not None and soc:
+        proc["range_at_100"] = _phys(round(100 * float(range_at_soc) / float(soc), 1), "km")
+
     # ── add computed fields here ──────────────────────────────────────────
     # Use _get(record, "domain", "statusObject", "field", "value") to
     # safely read any nested value.  Always use {"value": ..., "unit": ...}