feat: fire halt broadcast + tombstone all-clear (wildfire_halted / wildfire_closed)

Enable _maybe_emit_halt in firms_handler (remove return None stub) so
fires with no FIRMS hotspot activity beyond halt_minimum_seconds emit a
routine wildfire_halted broadcast.

Add tombstone all-clear in wfigs_handler: when a fire is tombstoned and
has last_broadcast_at set (i.e. previously made it to mesh), broadcast a
wildfire_closed message with acres, containment, and location. Fires that
were never broadcast are silently consumed.

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

meshai/central/firms_handler.py

@@ -774,7 +774,6 @@ def _maybe_emit_halt(conn, *, data, now):
     eligible because we filter on `halt_broadcast_at IS NULL OR
     halt_broadcast_at < last_pass_at`.
     """
-    return None
     minimum_s = int(adapter_config.fires.halt_minimum_seconds)
     cutoff = float(now) - float(minimum_s)
     row = conn.execute(

meshai/central/wfigs_handler.py

@@ -116,6 +116,40 @@ def handle_wfigs(normalized: dict, envelope: dict, subject: str,
                 )
             except Exception:
                 logger.exception("wfigs: tombstoned_at stamp failed irwin=%s", irwin_id)
+
+        # All-clear broadcast: only fires that previously made it to mesh
+        # get a closure message. Silent for fires that were never broadcast.
+        if kind == "wfigs_tombstone" and irwin_id:
+            fire_row = conn.execute(
+                "SELECT incident_name, current_acres, current_contained_pct, "
+                "last_broadcast_at, county, state, lat, lon "
+                "FROM fires WHERE irwin_id = ?", (irwin_id,)
+            ).fetchone()
+            if fire_row is not None and fire_row["last_broadcast_at"] is not None:
+                name = fire_row["incident_name"] or "(unnamed fire)"
+                # Build line 2 parts
+                parts = []
+                if fire_row["current_acres"] is not None:
+                    parts.append(f"{int(fire_row['current_acres']):,} ac")
+                if fire_row["current_contained_pct"] is not None:
+                    parts.append(f"{int(fire_row['current_contained_pct'])}% contained")
+                # Location via _location_anchor with a minimal normalized dict
+                loc_dict = {
+                    "lat": fire_row["lat"], "lon": fire_row["lon"],
+                    "county": fire_row["county"], "state": fire_row["state"],
+                }
+                anchor = _location_anchor(loc_dict)
+                if anchor and anchor != "(location unknown)":
+                    parts.append(anchor)
+                lines = [f"✅ {name} — contained & closed"]
+                if parts:
+                    lines.append(" | ".join(parts))
+                wire = "\n".join(lines)
+                if isinstance(data, dict):
+                    data["category"] = "wildfire_closed"
+                    data["_severity_override"] = "routine"
+                return wire
+
         return None
 
     # ---- active incident ----