Autocomplete crashes on CR-only line endings

[bolexyro]

Description

Autocomplete crashes when the query text contains carriage-return-only (\r) line endings. This can occur after pasting multiline SQL on Windows and then editing the query, which triggers autocomplete.

Environment

• sqlit-tui: 1.5.2
• OS: Windows

Steps to reproduce

1. Paste multiline text whose lines are separated by \r, for example:

SELECT
    a.attname AS column_name,
    format_type(a.atttypid, a.atttypmod) AS data_type
FROM
    pg_catalog.pg_attribute a
JOIN
    pg_catalog.pg_class c ON a.attrelid = c.oid
WHERE
    c.relname = 'users'
    AND a.attnum > 0
    AND NOT a.attisdropped;

2. Edit the text (for example, press Backspace) so autocomplete runs.

Actual behavior

sqlit crashes in AutocompleteMixin._location_to_offset:

IndexError: list index out of range
  File "sqlit/domains/query/ui/mixins/autocomplete.py", line 92
    offset = sum(len(lines[i]) + 1 for i in range(row))

The editor reports a cursor location such as (8, 21), while text.split("\n") returns only one line because the text contains \r separators.

Expected behavior

Autocomplete should handle LF, CRLF, and CR-only line endings without crashing, and cursor locations should round-trip correctly.

Reproduction result

Tested directly against 1.5.2:

• LF (\n): works
• CRLF (\r\n): works
• CR-only (\r): reproduces the IndexError