feat(tools): count aircraft in an area by airline

OpenSky, the default civil feed, reports no operator, so group_by: operator
said "no operator reported". aircraft_in_area now also takes
group_by: 'airline', read from the ICAO designator in each callsign: three
letters followed by a flight number that starts with a digit (SWA1234,
UAL12A). Registrations used as callsigns (N123AB) count as unknown. Rows are
unchanged; the designator is derived for the breakdown only.

Live, Texas: "785 aircraft ...; most by airline: AAL (89), SWA (65), UAL (52);
283 unknown."

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/CURRENT-STATE.md

@@ -98,10 +98,11 @@ combined situation brief, military awareness around a point, the app's heads-up
 opens the app over an area. Tools reuse the layers' portable source factories, take a
 shared `area` argument (place name, bounding box, or point and radius) and cap
 lists at 25 rows by default. `aircraft_in_area` and `vessels_in_area` can also
-count every match by a field (`group_by`: operator, country or type for
-aircraft; type or destination for ships; the ten largest groups, then other and
-unknown counts; the summary says when a feed reports none of the field) and
-summarize airborne altitude and speed (`stats`: count, min, median, mean, max).
+count every match by a field (`group_by`: airline, read from the ICAO
+designator in the callsign, or operator, country or type for aircraft; type or
+destination for ships; the ten largest groups, then other and unknown counts;
+the summary says when a feed reports none of the field) and summarize airborne
+altitude and speed (`stats`: count, min, median, mean, max).
 Both cover all matches, not just the rows returned; voice leaves these two
 tools out, so they reach MCP clients only. Voice offers the same queries next to its app
 actions: the session lists them, and the browser runs them through the same