[alexey-rsi]

Overview

Support Python Jinja's \xHH escapes in string literals, including templates that remove NUL characters with replace("\x00", ""). Escapes consume exactly two hexadecimal digits and encode the character as UTF-8; invalid or incomplete escapes produce a lexer error.

Additional information

• test-jinja: 1,504 assertions pass, zero failures; eight tests skipped.
• Regressions cover NUL removal, non-ASCII escapes, exactly two hex digits, escaped backslashes, and malformed escapes.
• All 256 values with uppercase/lowercase hex digits and 551 full-template rendering cases match Python Jinja. Both implementations reject the nine malformed cases checked.

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure: YES. Codex substantially assisted implementation, review, testing. Code has been manually reviewed and the PR description has been written manually.