* feat(panel): show dual quota capsules with compact provider icons

Place provider identity beside primary/secondary capsules in both panel styles.
Keep explicit lane selections, show vertical meters, and evaluate visibility
against either displayed quota. Include tooltip and accessible quota details.

Documentation impact: update usage, README screenshots, development smoke
coverage, TODO scope, Unreleased, configuration help, and all five catalogs.

Validation: strict make check in the pinned KDE neon CI container, no skips;
make package; focused OpenGL captures and Qt layout/interaction tests.

* test(panel): accept the intentionally absent secondary quota