Fix linting error: Add TestTruncateSessionID test calling sanitize.TruncateSessionID

The test was added in main branch but was calling the function directly from the
auth package. Since the function was moved to sanitize package, the test now
correctly calls sanitize.TruncateSessionID.

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

internal/auth/header_test.go

@@ -344,3 +344,81 @@ func TestExtractSessionID(t *testing.T) {
 		})
 	}
 }
+
+func TestTruncateSessionID(t *testing.T) {
+	assert := assert.New(t)
+
+	tests := []struct {
+		name      string
+		sessionID string
+		want      string
+	}{
+		{
+			name:      "Empty session ID returns (none)",
+			sessionID: "",
+			want:      "(none)",
+		},
+		{
+			name:      "Single character",
+			sessionID: "a",
+			want:      "a",
+		},
+		{
+			name:      "Short session ID (5 chars)",
+			sessionID: "abc12",
+			want:      "abc12",
+		},
+		{
+			name:      "Exactly 8 characters - not truncated",
+			sessionID: "abcd1234",
+			want:      "abcd1234",
+		},
+		{
+			name:      "Exactly 9 characters - truncated",
+			sessionID: "abcd12345",
+			want:      "abcd1234...",
+		},
+		{
+			name:      "Long session ID (>8 chars)",
+			sessionID: "my-session-id-12345",
+			want:      "my-sessi...",
+		},
+		{
+			name:      "Very long session ID",
+			sessionID: "my-super-long-session-id-with-many-characters-12345678901234567890",
+			want:      "my-super...",
+		},
+		{
+			name:      "Session ID with special characters",
+			sessionID: "key!@#$%^&*()",
+			want:      "key!@#$%...",
+		},
+		{
+			name:      "Session ID with unicode",
+			sessionID: "session-émojis-🔑",
+			want:      "session-...",
+		},
+		{
+			name:      "UUID format",
+			sessionID: "550e8400-e29b-41d4-a716-446655440000",
+			want:      "550e8400...",
+		},
+		{
+			name:      "Whitespace only (under 8 chars)",
+			sessionID: "   ",
+			want:      "   ",
+		},
+		{
+			name:      "Whitespace only (over 8 chars)",
+			sessionID: "         ",
+			want:      "        ...",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := sanitize.TruncateSessionID(tt.sessionID)
+			assert.Equal(tt.want, got)
+		})
+	}
+}