[BUG] False positive "lone slash in escape sequence" with \\" in triple-quoted strings

[MrAMS]

Description:

The LSP incorrectly parses \\" inside triple-quoted strings. It treats \\ as an escaped backslash and then interprets the following " as a string terminator, causing false errors.

Minimal reproduction:

_TEMPLATE = """
echo 'print("#include \\"" + f + "\\"")'
"""

Errors reported:

• lone slash in escape sequence
• String literal is not terminated

Expected: No errors. The \\" should produce a literal \" in the output, not terminate the string.

Related issue zed-starlark/issues/17