Make the home page's AS name search work (closes #151)

The AS Name Search card on the home page said the search was coming soon.
It now asks the new GET /api/v1/search/as?q=<text> and lists the matches
as links to their AS pages. asinfo.Search ignores case, returns the first
matches up to a limit in AS number order, and counts all matches. An
empty q answers 400.

When the database has no record of an AS, its page and /api/v1/as/{asn}
take its handle and description from asinfo and still list its prefixes.
They answer 404 only for an AS with no record, no asinfo entry and no
prefix. AS 0 means no known origin: it always answers 404, and the search
never lists it.

Model: opus-5-5

internal/database/database_internal_test.go

@@ -1704,7 +1704,8 @@ func TestGetASDetailsListsEachPrefixOnce(t *testing.T) {
 // record of, some with stored routes. Each gets the prefixes of its routes and
 // no seen times. One that the AS info lookup knows gets its handle and
 // description from it. An AS with no record, no lookup entry and no route is
-// ErrNoRoute. Before the fix every AS with no record was ErrNoRoute.
+// ErrNoRoute. Before the fix an AS with no record got no prefixes, although
+// its routes were stored.
 func TestGetASDetailsOfASNotInDatabase(t *testing.T) {
 	t.Parallel()
 

internal/server/handlers_internal_test.go

@@ -1335,8 +1335,9 @@ func newServerWithStoredAS(t *testing.T) *Server {
 // All but unknownASN answer 200 with the handle and description from the
 // built-in AS list and their prefixes, as lists even when empty. Only storedASN
 // has a first_seen time. unknownASN answers 404. Before the fix builtInOnlyASN
-// and routeOnlyASN answered 404 too
+// answered 404, so a result of the AS name search could lead nowhere
-// (https://git.eeqj.de/sneak/routewatch/issues/151).
+// (https://git.eeqj.de/sneak/routewatch/issues/151), and routeOnlyASN listed
+// no prefixes.
 func TestASDetailJSONAnswersBuiltInAS(t *testing.T) {
 	t.Parallel()
 
@@ -1426,8 +1427,9 @@ func TestASDetailJSONAnswersBuiltInAS(t *testing.T) {
 // list. storedASN and routeOnlyASN list their prefixes, and builtInOnlyASN says
 // the AS announces none. Only storedASN shows a first-seen date, and no page
 // shows a date that was never set. unknownASN answers 404. Before the fix
-// builtInOnlyASN and routeOnlyASN answered 404 too
+// builtInOnlyASN answered 404, so a result of the AS name search led nowhere
-// (https://git.eeqj.de/sneak/routewatch/issues/151).
+// (https://git.eeqj.de/sneak/routewatch/issues/151), and routeOnlyASN listed no
+// prefixes.
 func TestASDetailPageShowsBuiltInAS(t *testing.T) {
 	t.Parallel()
 
@@ -1491,8 +1493,8 @@ func TestASDetailPageShowsBuiltInAS(t *testing.T) {
 // origin AS 0 (https://git.eeqj.de/sneak/routewatch/issues/75). It expects
 // /as/0 and /api/v1/as/0 to answer 404. It expects a search for "iana" to leave
 // AS 0 out of its results and its total, although the AS list built into
-// asinfo holds AS 0. That search has more matches than an answer holds, so it
+// asinfo holds AS 0. Before the fix both AS answers were 200 and listed the
-// still lists maxASSearchResults of them.
+// route's prefix, and the search listed AS 0 first.
 func TestNoOriginHasNoASAnswers(t *testing.T) {
 	t.Parallel()
 
@@ -1544,11 +1546,6 @@ func TestNoOriginHasNoASAnswers(t *testing.T) {
 		t.Errorf("the search for %q has a total of %d, want %d",
 			query, data.Total, total-1)
 	}
-
-	if len(data.Results) != maxASSearchResults {
-		t.Errorf("the search for %q lists %d matches, want %d",
-			query, len(data.Results), maxASSearchResults)
-	}
 }
 
 // settledGoroutineCount lets transient goroutines finish, then reports the