fix: handle single-line comments in template code blocks

[harunosakura030303-maker]

Summary

Fixes #337 — unpaired apostrophes in single-line comments (// it's, // don't) no longer cause parse errors.

Problem

The parser's parseCloseReg regex matches ', ", `, /*, and closing tags. When it encounters a ' inside a // comment, it tries to match a complete string literal and fails with "unclosed string" since the apostrophe is unpaired.

Fix

Added // to parseCloseReg and a handler that skips to end of line when a single-line comment is encountered, matching the existing /* */ block comment behavior.

Test Case

const eta = new Eta();
const result = eta.renderString(`<%
  const foo = 'bar';
  // This comment with unpaired apostrophe: it's fixed
  console.log(foo);
%><%= foo %>`, {});
// Should output: "bar"