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.go

@@ -21,6 +21,7 @@ import (
 
 	"git.eeqj.de/sneak/routewatch/internal/config"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
+	"git.eeqj.de/sneak/routewatch/internal/ristypes"
 	"git.eeqj.de/sneak/routewatch/pkg/asinfo"
 	_ "github.com/mattn/go-sqlite3" // CGO SQLite driver
 )
@@ -1748,9 +1749,21 @@ func (d *Database) GetASDetails(asn int) (*ASN, []LiveRoute, error) {
 // GetASDetailsContext returns the AS and the prefixes it originates, the IPv4
 // ones first, each once with the time of its newest route. It makes two index
 // searches per prefix, however many peers carry the prefix.
+//
+// The routes of an AS can be stored before its record in the asns table. When
+// the AS has no record, its handle and description come from the AS info
+// lookup, and it has no seen times. An AS with no record, no lookup entry and
+// no prefix is ErrNoRoute.
+//
+// ristypes.NoOrigin means no known origin, not an AS, so it is ErrNoRoute
+// whatever is stored.
 func (d *Database) GetASDetailsContext(
 	ctx context.Context, asn int,
 ) (*ASN, []LiveRoute, error) {
+	if asn == ristypes.NoOrigin {
+		return nil, nil, fmt.Errorf("%w: AS%d", ErrNoRoute, asn)
+	}
+
 	// Get AS information
 	var (
 		asnInfo             ASN
@@ -1763,17 +1776,28 @@ func (d *Database) GetASDetailsContext(
 		asn,
 	).Scan(&asnInfo.ASN, &handle, &description, &asnInfo.FirstSeen,
 		&asnInfo.LastSeen)
-	if err != nil {
-		if errors.Is(err, sql.ErrNoRows) {
-			return nil, nil, fmt.Errorf("%w: AS%d", ErrNoRoute, asn)
+
+	// known is whether the asns table or the AS info lookup holds the AS.
+	known := true
+
+	switch {
+	case errors.Is(err, sql.ErrNoRows):
+		asnInfo.ASN = asn
+
+		info, ok := asinfo.Get(asn)
+		if ok {
+			asnInfo.Handle = info.Handle
+			asnInfo.Description = info.Description
 		}
 
+		known = ok
+	case err != nil:
 		return nil, nil, fmt.Errorf("failed to query AS: %w", err)
+	default:
+		asnInfo.Handle = handle.String
+		asnInfo.Description = description.String
 	}
 
-	asnInfo.Handle = handle.String
-	asnInfo.Description = description.String
-
 	allPrefixes, err := d.originPrefixes(ctx, asn, ipVersionV4)
 	if err != nil {
 		return &asnInfo, nil, err
@@ -1784,7 +1808,13 @@ func (d *Database) GetASDetailsContext(
 		return &asnInfo, allPrefixes, err
 	}
 
-	return &asnInfo, append(allPrefixes, prefixesV6...), nil
+	allPrefixes = append(allPrefixes, prefixesV6...)
+
+	if !known && len(allPrefixes) == 0 {
+		return nil, nil, fmt.Errorf("%w: AS%d", ErrNoRoute, asn)
+	}
+
+	return &asnInfo, allPrefixes, nil
 }
 
 // ASPeer represents a peering relationship with another AS including handle,