fix(tools): exclude unknown altitude from requested aircraft bands (#1115)

aircraft_in_area compared a nullable altitude, so a contact with neither barometric nor geometric altitude matched max_altitude_m as though it were at zero. Require a reported finite altitude only when a band is requested; unfiltered queries keep the contact.

docs/CURRENT-STATE.md

@@ -100,6 +100,9 @@ shared `area` argument (place name, bounding box, or point and radius) and cap
 lists at 25 rows by default. Voice offers the same queries next to its app
 actions: the session lists them, and the browser runs them through the same
 catalog, loaded on first use. See [tools and the MCP server](TOOLS.md).
+Aircraft altitude-band queries require a reported barometric or geometric altitude
+for each match, so a grounded contact that reports none is left out of a band too.
+Queries without an altitude band retain unknown-altitude contacts.
 
 Catalog calls check their cancellation signal immediately before executing a
 tool. Already-cancelled queries do not start; cancellation after execution starts