docs: the history phrases the id sweep missed, restated as present-tense facts or traps (#6277)

A wider pass for "previous", "before the fix", "we shipped" and the
like. The chi double-subtree, uppercase Vorbis key and stopPropagation
comments now describe the trap they guard; commit hashes, CI run
numbers and a deleted file name are gone; uuidString's comment says
what it returns.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/auth/clientip_test.go

@@ -34,8 +34,8 @@ func TestClientIP(t *testing.T) {
 		},
 		{
 			// The common case: one TLS-terminating proxy. Note RemoteAddr is
-			// PUBLIC here — a proxy on its own host — which the previous
-			// private-range heuristic got wrong.
+			// PUBLIC here — a proxy on its own host — which a private-range
+			// heuristic would get wrong.
 			name:       "one proxy on a public address yields the client",
 			hops:       1,
 			remoteAddr: "203.0.113.200:40000",