Make "Last Started" date format on dashboard match "Last Updated"

[Copilot]

The "Status" panel on the main dashboard showed "Last Updated" and "Last Started" in two visually inconsistent formats right next to each other (2026-07-10 14:40:10.512590 vs 2026-07-10T01:10:39+0100).

Display fix

• In get_status_html (web.py), last_started is now parsed with str2time and stripped of tzinfo before rendering, so it displays without the ISO T separator or timezone offset — matching the style of last_updated.
• Storage of last_started is untouched (output.py still writes it via TIME_FORMAT); this is a display-only change.
• Parse failures are now logged via self.log() instead of being silently swallowed.

last_started = self.get_state_wrapper(self.prefix + ".last_started", default=None)
if last_started:
    try:
        last_started = str2time(last_started).replace(tzinfo=None)
    except (ValueError, TypeError) as e:
        self.log("Warn: Failed to parse last_started time {}: {}".format(last_started, e))

Tests

• Added a case in test_web_functions.py covering get_status_html rendering, asserting the reformatted value appears and the raw ISO/timezone form does not.

[Copilot]

Pull request overview

This PR makes the “Last Started” timestamp in the web dashboard’s Status panel render in the same human-readable style as “Last Updated” (space-separated datetime without ISO T or timezone offset), while keeping the stored sensor value unchanged.

Changes:

• Parse last_started in WebInterface.get_status_html() via str2time() and render it without tzinfo to match the adjacent last_updated style.
• Log parse failures for last_started instead of silently swallowing them.
• Add a web functions test to assert the reformatted “Last Started” output is shown and the raw stored ISO+offset form is not.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
apps/predbat/web.py	Normalizes last_started display formatting in the status HTML and logs parse failures.
apps/predbat/tests/test_web_functions.py	Adds coverage asserting get_status_html() renders “Last Started” in the expected format.