Rewrite the README sentences that fail the prose rules or disagree with the code

A fresh read of README.md whole against the rules of issue 157, with every
statement except measured figures checked against the code on next. Four
sentences fail the prose rules, all in sections added since 742e759: the
origin change definition, the first uses of TTL and SOA record, and the
geojs request. Five disagree with the code: the geojs request carries only
the addresses the cache does not hold; after a write fails on SQLite's hard
heap limit, the prefix handler also writes its origin changes again, and
the PTR and geolocation caches write their answers again; the test rerun on
failure drops -cover; and latitude and longitude are in degrees, which
their names do not say.

Model: fable-5-1

TODO.md

@@ -59,10 +59,12 @@ File an issue for each problem the run finds.
 
 - 2026-11-10: `README.md` and this file are read whole against the rules of
   https://git.eeqj.de/sneak/routewatch/issues/157, and every statement except
-  measured figures and what outside services do is checked against the code on
-  `next`. Four README sentences failed the prose rules. Five disagreed with the
-  code. Each is rewritten. Status and Next Step describe the live-feed run in
-  progress (closes https://git.eeqj.de/sneak/routewatch/issues/251).
+  measured figures is checked against the code on `next`. Four README sentences
+  failed the prose rules, on origin changes, PTR lookups and geolocation, and
+  five disagreed with the code, on units, geolocation, a failed database write
+  and `script/test`. Each is rewritten. Status and Next Step describe the
+  live-feed run in progress (closes
+  https://git.eeqj.de/sneak/routewatch/issues/251).
 - 2026-11-10: the image creates the `routewatch` user as a regular user with UID
   1000, so the build no longer warns about the system UID range (closes
   https://git.eeqj.de/sneak/routewatch/issues/248).