fix: encode special characters in HTMLElement textContent setter

[spokodev]

The HTMLElement.textContent setter stored the raw string in a text node without escaping, so special characters were re-interpreted as markup:

el.textContent = '<b>Tom & Jerry</b>';
el.innerHTML // '<b>Tom & Jerry</b>'  (expected the escaped text)

el.textContent = '<script>alert(1)</script>'; // re-parses into a real <script> element

The base Node.textContent setter already encodes the value (cb11eab); the HTMLElement override was missed. Encode the value before storing it.

[taoqf]

1) HTMLElement#textContent setter encodes special characters
       escapes HTML metacharacters when serialized:

      AssertionError: expected '<b>Tom & Jerry</b>' to equal '&lt;b&gt;Tom &amp; Jerry&lt;/b&gt;'
      + expected - actual

      -<b>Tom & Jerry</b>
      +&lt;b&gt;Tom &amp; Jerry&lt;/b&gt;
      
      at Assertion.fail (test/node_modules/should/cjs/should.js:275:17)
      at Assertion.value (test/node_modules/should/cjs/should.js:356:19)
      at Context.<anonymous> (test/tests/textcontent-encode.js:8:24)
      at process.processImmediate (node:internal/timers:504:21)

  2) HTMLElement#textContent setter encodes special characters
       round-trips a text value that looks like markup:

      AssertionError: expected 'alert(1)' to equal '<script>alert(1)</script>'
      + expected - actual

      -alert(1)
      +<script>alert(1)</script>
      
      at Assertion.fail (test/node_modules/should/cjs/should.js:275:17)
      at Assertion.value (test/node_modules/should/cjs/should.js:356:19)
      at Context.<anonymous> (test/tests/textcontent-encode.js:17:31)
      at process.processImmediate (node:internal/timers:504:21)

Seems unit test went wrong.

[spokodev]

Both assertions pass once dist/ is rebuilt from this branch. test:dist runs against the compiled dist/, and neither test nor pretest recompiles, so a stale dist/ shows the old (unencoded) behavior. On current main with this change:

bun install && (cd test && bun install)
bun run build
bun run test:dist

→ 267 passing, including both textContent setter encodes special characters cases. The patch is unchanged; I can rebase onto main if that's easier to verify.

[spokodev]

Rebased onto main — CI is green now (build 22/24/26.x). The earlier red was a stale base (the old yarn lockfile), not the change itself. Ready for another look.