chore(tools): the live tools take their target, they do not assume it

The dashboard's fifth guard learned to see a host name and found three in
tools/live: a default host in lib.ts and two health checks written out.
A measuring tool that aims at somebody else's server by default is a trap,
so FILIUS_HOST has no fallback and the run says what to set; the two checks
use BASE, which is derived from it.

BASE had to be imported in m3.ts — without that this would have been a
NameError instead of the intended refusal.

README.md keeps the real names: the project is this school's and the prose
describes its deployment; what has to stand on its own is the code.

The allow file also excuses the simulator's own data. Filius simulates a
network, so its scenarios, tests and documentation carry 65 693 addresses
(measured) — all of invented machines in invented networks, which is the
point of the program. Deliberately broad: a list of scenario files would be
one nobody keeps correct.

typecheck green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/live/lib.ts

@@ -17,7 +17,11 @@ const env = Object.fromEntries(
     .filter((l) => l.includes('='))
     .map((l) => [l.slice(0, l.indexOf('=')).trim(), l.slice(l.indexOf('=') + 1).trim()]),
 );
-export const HOST = process.env.FILIUS_HOST ?? 'test-filius.hub.mdg-hamburg.de';
+// No deployment's host as a fallback: this repository is handed out, and
+// a measuring tool that aims at somebody else's server by default is a
+// trap. Unset, the run says what to set.
+export const HOST = process.env.FILIUS_HOST ?? '';
+if (!HOST) throw new Error('set FILIUS_HOST to the instance to measure');
 export const BASE = `https://${HOST}`;
 const SECRET = env.FILIUS_TICKET_SECRET!;
 const KEY = env.FILIUS_SERVICE_KEY!;