* feat(settings): simplify panel controls with progressive disclosure

Keep appearance and contents visible, with quota, order, conditions, and automatic provider selection in a collapsed section. Preserve pending values and show customized options in its summary. Restore preview capsules by resolving delegate records to synthetic source rows.

Documentation: update usage, README, settings decisions, development checks, changelog, translations, and the completed TODO description. Verified strict make check, packaging, keyboard interactions, and three native Plasma settings scenarios.

* feat(panel): group optional text with provider meters

Keep appearance and meters first; move selected-provider details into a local disclosure with retained preferences. Preserve custom element ordering and filtered-meter identity fallbacks.

Update usage, README, settings rationale, TODO summary, screenshot index, translations and existing regression contracts. Verified strict make check, make package, native keyboard settings tests and seven targeted OpenGL scenarios.

* fix(panel): stabilize reordered settings and preserve crowded text

Address both CodeRabbit findings with a positive-width fallback and control-specific parity assertions. Isolate the element-order layout from FormLayout size-hint queries to avoid the reproduced Qt layout-polish crash.

Update usage, development, settings rationale and Unreleased notes. CLI contracts, configuration, translations and TODO scope are unchanged. Verified strict make check, make package, 57 smoke scenarios, native reorder/focus tests and 12 debugger runs of the failing scenario.