fix: stop appending a stray '<' to unterminated block-text elements

[spokodev]

An unterminated raw-text element (script/style/pre) with no closing tag keeps a stray < in its text:

parse('<script>var a = 1;', { script: true }) // text 'var a = 1;<'  (expected 'var a = 1;')
parse('<style>.a{color:red}')                 // text '.a{color:red}<'

dataEndPos was computed from the opening wrapper length, but the closing sentinel is one character longer, so the < of the sentinel was included when the element has no closing tag. Off by one in the EOF branch.

[taoqf]

1. unterminated block-text elements
   does not append a stray "<" to an unclosed <script>:

   AssertionError: expected 'var a = 1;<' to equal 'var a = 1;'

   • expected - actual

   -var a = 1;<
   +var a = 1;

   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. (test/tests/incomplete-blocktext.js:8:22)
   at process.processImmediate (node:internal/timers:504:21)

2. unterminated block-text elements
   does not append a stray "<" to an unclosed <style>:

   AssertionError: expected '.a{color:red}<' to equal '.a{color:red}'

   • expected - actual

   -.a{color:red}<
   +.a{color:red}

   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. (test/tests/incomplete-blocktext.js:14:21)
   at process.processImmediate (node:internal/timers:504:21)

[spokodev]

This passes once dist/ is rebuilt from the branch — test:dist runs against the compiled dist/, which the test/pretest scripts don't recompile, so a stale build still shows the trailing <. On current main with this change, bun run build && bun run test:dist gives 267 passing (0 failing), including both unterminated block-text elements cases, and the dataEndPos change causes no other regressions.