Move to Go 1.27, and fix initials for non-ASCII names

Initials() capped the loop with len(out) == 2, which counts bytes: a name
starting with Ä, Ö or Å filled the budget on its own and returned a single
letter. Count the initials taken instead.

go fix also wanted a strings.Builder here, but that allocates a string per
iteration to measure a two-character result. Took its SplitSeq suggestion
in lyrics.go, which drops an intermediate slice.

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.26-alpine AS build
+FROM golang:1.27-alpine AS build
 # CalVer, injected at build so no file needs bumping by hand: docker build --build-arg VERSION=…
 ARG VERSION=dev
 WORKDIR /src

auth.go

@@ -35,10 +35,11 @@ type member struct {
 
 // Initials for the avatar circle: no default image on disk, no identicon generator.
 func (m *member) Initials() string {
-	out := ""
+	out, n := "", 0
 	for _, f := range strings.Fields(m.Name) {
 		out += strings.ToUpper(string([]rune(f)[0]))
-		if len(out) == 2 {
+		// ponytail: count runes taken, not bytes — "Ä" is 2 bytes and used to end the loop early.
+		if n++; n == 2 {
 			break
 		}
 	}

auth_test.go

@@ -230,3 +230,17 @@ func TestBanDropsSessionsAndBlocksLogin(t *testing.T) {
 		t.Fatalf("login after unban: status = %d, want 303", w.Code)
 	}
 }
+
+func TestInitials(t *testing.T) {
+	for name, want := range map[string]string{
+		"Esa Kataja":  "EK",
+		"Ärväs Öhman": "ÄÖ", // multi-byte initials must not end the loop early
+		"Åke":         "Å",
+		"":            "",
+		"a b c":       "AB",
+	} {
+		if got := (&member{Name: name}).Initials(); got != want {
+			t.Errorf("Initials(%q) = %q, want %q", name, got, want)
+		}
+	}
+}

go.mod

@@ -1,6 +1,6 @@
 module git.kessinen.com/kessinen/levyraati26-go
 
-go 1.25.0
+go 1.27.0
 
 require (
 	golang.org/x/crypto v0.32.0

lyrics.go

@@ -67,7 +67,7 @@ func parseLRC(s string) []lyricLine {
 		return nil
 	}
 	var out []lyricLine
-	for _, raw := range strings.Split(s, "\n") {
+	for raw := range strings.SplitSeq(s, "\n") {
 		stamps := lrcOne.FindAllStringSubmatch(raw, -1)
 		if len(stamps) == 0 {
 			continue