Show the prefix page's origin names from the prefix query (closes #67)

The prefix page looked up each origin AS's details only to show its handle and description, and that lookup reads every live route the AS originates. `GetPrefixDetailsContext` already selected the handle and description and dropped them; it now returns them keyed by AS number, and the page uses them. The origin list now also shows the description after the handle, which it never rendered. The JSON prefix answer is unchanged. The test serves the page from a store whose AS lookup always fails.

Model: opus-5-5

internal/routewatch/app_integration_test.go

@@ -252,13 +252,15 @@ func (m *mockStore) GetASDetailsContext(ctx context.Context, asn int) (*database
 }
 
 // GetPrefixDetails mock implementation
-func (m *mockStore) GetPrefixDetails(prefix string) ([]database.LiveRoute, error) {
+func (m *mockStore) GetPrefixDetails(prefix string) ([]database.LiveRoute, map[int]database.ASN, error) {
 	// Return empty routes for now
-	return []database.LiveRoute{}, nil
+	return []database.LiveRoute{}, map[int]database.ASN{}, nil
 }
 
 // GetPrefixDetailsContext mock implementation with context support
-func (m *mockStore) GetPrefixDetailsContext(ctx context.Context, prefix string) ([]database.LiveRoute, error) {
+func (m *mockStore) GetPrefixDetailsContext(
+	ctx context.Context, prefix string,
+) ([]database.LiveRoute, map[int]database.ASN, error) {
 	return m.GetPrefixDetails(prefix)
 }
 

internal/routewatch/prefixhandler_test.go

@@ -170,7 +170,7 @@ func TestPrefixHandlerAppliesEachPeersLastUpdateInABatch(t *testing.T) {
 			}
 
 			ctx := context.Background()
-			routes, err := db.GetPrefixDetailsContext(ctx, prefix)
+			routes, _, err := db.GetPrefixDetailsContext(ctx, prefix)
 			if err != nil && !errors.Is(err, database.ErrNoRoute) {
 				t.Fatalf("GetPrefixDetailsContext: %v", err)
 			}