feat(users): always capitalise a display name's first letter

Andreas signed up as "andreas" and was shown that way everywhere. A name
is now capitalised on the way in — the first letter of each word raised,
the rest left as typed — in CreateUser (signup and invite-accept) and
UpdateProfile, so display, mail and export all agree.

Existing accounts are fixed by an idempotent startup pass
(NormalizeUserNames), the same shape as SealNotes: the rule is Unicode-aware
and per word, which SQLite's UPPER cannot spell, so it lives in Go rather
than a migration.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/store/names_test.go

@@ -0,0 +1,81 @@
+package store
+
+import (
+	"context"
+	"testing"
+)
+
+func TestNormalizeName(t *testing.T) {
+	cases := map[string]string{
+		"andreas":        "Andreas",
+		"Andreas":        "Andreas",
+		"anne mette":     "Anne Mette",
+		"  kristian  ":   "Kristian",
+		"anne   mette":   "Anne Mette",
+		"McDonald":       "McDonald", // an existing inner capital is kept
+		"óscar":          "Óscar",    // Unicode initial
+		"æblegaard":      "Æblegaard",
+		"":               "",
+		"   ":            "",
+		"mette-marie sø": "Mette-marie Sø", // only word-initials are raised
+		"iPhone listen":  "IPhone Listen",  // deliberately: the first letter is raised
+	}
+	for in, want := range cases {
+		if got := NormalizeName(in); got != want {
+			t.Errorf("NormalizeName(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestCreateUserCapitalisesName(t *testing.T) {
+	db := openTest(t)
+	ctx := context.Background()
+
+	u := &User{Email: "andreas@example.dk", Name: "andreas", PasswordHash: "x"}
+	if err := db.CreateUser(ctx, u, "Inbox"); err != nil {
+		t.Fatalf("create user: %v", err)
+	}
+	got, err := db.UserByEmail(ctx, "andreas@example.dk")
+	if err != nil {
+		t.Fatalf("read back: %v", err)
+	}
+	if got.Name != "Andreas" {
+		t.Errorf("stored name = %q, want %q", got.Name, "Andreas")
+	}
+}
+
+func TestNormalizeUserNamesBackfill(t *testing.T) {
+	db := openTest(t)
+	ctx := context.Background()
+
+	// An account as it looked before the app capitalised names: made properly,
+	// then set back to lower case behind the store's back to stand in for an old row.
+	u := &User{Email: "a@example.dk", Name: "Andreas", PasswordHash: "x"}
+	if err := db.CreateUser(ctx, u, "Inbox"); err != nil {
+		t.Fatalf("create user: %v", err)
+	}
+	if _, err := db.ExecContext(ctx, `UPDATE users SET name = 'andreas' WHERE id = ?`, u.ID); err != nil {
+		t.Fatalf("downgrade name: %v", err)
+	}
+
+	fixed, err := db.NormalizeUserNames(ctx)
+	if err != nil {
+		t.Fatalf("normalize: %v", err)
+	}
+	if fixed != 1 {
+		t.Fatalf("fixed = %d, want 1", fixed)
+	}
+	got, _ := db.UserByID(ctx, u.ID)
+	if got.Name != "Andreas" {
+		t.Errorf("name after backfill = %q, want %q", got.Name, "Andreas")
+	}
+
+	// Idempotent: nothing left to do on a second pass.
+	again, err := db.NormalizeUserNames(ctx)
+	if err != nil {
+		t.Fatalf("normalize again: %v", err)
+	}
+	if again != 0 {
+		t.Errorf("second pass fixed = %d, want 0", again)
+	}
+}