MINOR bump: Qobuz playlist sync is the headline feature (#677), plus
the Import album search fallback-source surfacing fix (#681).
* web_server.py — _SOULSYNC_BASE_VERSION → 2.6.0
* webui/static/helper.js — split the 2.5.9 'Unreleased — dev cycle'
entries into a new 2.6.0 block with a real release-date marker;
bumped the _getLatestWhatsNewVersion fallback default; rolled the
'2.5.9 Release Stability Pass' modal section down to a generic
'Earlier in v2.5' aggregator now that 2.6.0 is the current release
* .github/workflows/docker-publish.yml — bumped manual version_tag
default to 2.6.0 so the next workflow_dispatch defaults right
Broque Thomas
