fix: use formatToParts for locale-safe date formatting

Use Intl.DateTimeFormat.formatToParts() to extract locale-formatted
year/month/day values before reordering, ensuring non-Latin numeral
systems are handled correctly when date_format is overridden.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Andrew Grimberg <tykeal@bardicgrove.org>

Author: tykeal

.gitignore

@@ -9,7 +9,7 @@ custom_components/*/__pycache__/
 venv
 *.pyc
 .coverage
-coverage.xml
+coverage.*
 .tox
 ha-core/
 
@@ -23,3 +23,4 @@ package-lock.json
 .cursor/
 .aider*
 .continue/
+coverage/