Timeline: smwtlposition marker is silently ignored when no timelinebands are configured

[gesinn-it-gea]

Description

In formats/timeline/resources/ext.srf.timeline.js, smwMakeTimeline() builds the FullCalendar/SimileTimeline band(s) differently depending on whether any smwtlband markers were found:

• When bandcount > 0, each band is created via Timeline.createBandInfo({ ..., date: position, ... }) (lines ~110–129), correctly honoring a smwtlposition marker parsed into position.
• When bandcount === 0 (no timelinebands parameter set), the "default band" fallback at lines 136–145 builds its Timeline.createBandInfo({...}) call without a date option:

// default band
if ( bandcount === 0 ) {
    bandInfos[ 0 ] = Timeline.createBandInfo( {
        eventSource: eventSource,
        width: '100%',
        intervalUnit: Timeline.DateTime.MONTH,
        intervalPixels: 100,
        theme: theme
        // date: position  <-- missing
    } );
}

As a result, a smwtlposition marker (i.e. the timelineposition format parameter) has no effect whenever timelinebands is not configured — the timeline always opens at its default position instead of the requested one.

Steps to reproduce

Use {{#ask: ... |format=timeline |timelineposition=1970-01-01T00:00:00Z}} without setting timelinebands. The timeline ignores timelineposition and opens at today's date instead.

Expected behavior

The default band should also receive date: position, consistent with the bandcount > 0 branches.

Additional context

Found and pinned (without fixing) while adding node-qunit test coverage for this file in #1100 — see the test ext.srf.timeline.test.js > BUG: ignores the smwtlposition marker when no smwtlband is present (only the default band exists), which documents today's (incorrect) behavior so the suite doesn't fail until this is fixed.