fix: nws locations truncation — configurable word-boundary cap (default 120)

Replace hardcoded 40-char locations cap with adapter_config key
nws.locations_max_chars (default 120). Truncation now uses word-boundary
split with ellipsis, matching the swpc _trunc pattern.

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

meshai/adapter_config/defaults.py

@@ -571,6 +571,11 @@ REGISTRY: dict[tuple[str, str], dict[str, Any]] = {
         "type": "int",
         "description": "Allow re-broadcast of the same CAP id after this many seconds (the nws_handler relaxes its dedup gate past this point and uses an Active: prefix).",
     },
+    ("nws", "locations_max_chars"): {
+        "default": 120,
+        "type": "int",
+        "description": "Maximum characters for the locations field on line 4 of NWS wire. Truncates at word boundary.",
+    },
 
     # =================================================================
     # AVALANCHE -- 1 setting (min danger level broadcast floor)

meshai/central/nws_handler.py

@@ -384,8 +384,12 @@ def _render(*, event_type, area_desc, geocoder_city, county, state,
     compass, speed_mph = _parse_motion(params)
     motion = f"Moving {compass} {speed_mph} mph" if compass and speed_mph else ""
     locations = (desc.get("locations") or "").rstrip("., ")
-    if len(locations) > 40:
-        locations = locations[:37] + "..."
+    _loc_limit = int(adapter_config.nws.locations_max_chars)
+    if len(locations) > _loc_limit:
+        cut = locations[:_loc_limit].rsplit(" ", 1)[0]
+        if not cut:
+            cut = locations[:_loc_limit]
+        locations = cut + "\u2026"
     if motion and locations:
         line4 = f"{motion} — {locations}"
     elif motion: