Rewrite the README sentence by sentence (closes #157)

The README is rewritten from scratch against the prose rules of
#157: every sentence under
about 30 words, lists as bullets, every technical term defined where it
first appears, and every statement checked against the code on next. It
leads with what RouteWatch is and how to run it, then the pages, the API
and the blocklists, then the settings, memory and upaas, and last the
design and the development workflow. The dated entry goes into TODO.md.

Model: fable-5-1

TODO.md

@@ -41,9 +41,6 @@ https://git.eeqj.de/sneak/routewatch/issues/225, also on `next`, takes the peers
 whose sessions go down together out of the table in one walk. A 24-hour run of
 `9bd0e91` on the live feed is checking whether any handler still drops updates.
 
-The README rewrite, https://git.eeqj.de/sneak/routewatch/pulls/210, is being
-reworked. It is part of https://git.eeqj.de/sneak/routewatch/issues/157.
-
 Two questions wait for sneak: which history the prefix page keeps
 (https://git.eeqj.de/sneak/routewatch/issues/161), and which fields the IP
 lookup answer gains (https://git.eeqj.de/sneak/routewatch/issues/203).
@@ -60,6 +57,9 @@ problem the run finds.
 
 # Completed Steps
 
+- 2026-11-02: `README.md` is rewritten from scratch, sentence by sentence,
+  against the rules of https://git.eeqj.de/sneak/routewatch/issues/157. Every
+  statement was checked against the code on `next` (closes #157)
 - 2026-11-02: `TODO.md` is rewritten from scratch, sentence by sentence, against
   the rules of https://git.eeqj.de/sneak/routewatch/issues/157. Every Completed
   Steps entry keeps its date, its facts and its issue. Status and Next Step
@@ -424,7 +424,3 @@ problem the run finds.
 - 2025-07-27: The first commit: RouteWatch, a BGP stream monitor
 
 # Future Steps
-
-- Merge https://git.eeqj.de/sneak/routewatch/pulls/210 once a review passes. As
-  the last of the two PRs for https://git.eeqj.de/sneak/routewatch/issues/157 to
-  merge, it closes the issue.

internal/server/middleware_internal_test.go

@@ -261,7 +261,7 @@ func checkAnswerCarriesMeta(
 ) {
 	t.Helper()
 
-	// The values README "API v1" gives the two fields that never change.
+	// The values README "JSON API" gives the two fields that never change.
 	const (
 		wantTimeZone   = "UTC"
 		wantAPIVersion = 1