fix(ui): improve collapse accordion accessibility

[wyf027]

Summary

• Add accordion semantics to Collapse triggers with aria-expanded and aria-controls.
• Add generated trigger/panel ids and expose expanded content as named region panels.
• Hide the visual expand/collapse glyph from the button accessible name.
• Add Collapse tests for trigger-panel linkage, toggling, accordion mode, and disabled panels.
• Update Collapse docs with accessibility behavior and precise string[] API types.

Gap Notes

• Ant Design Collapse documents accordion mode and semantic DOM customization: https://ant.design/components/collapse/
• Element Plus Collapse exposes controlled active names and disabled accordion items: https://element-plus.org/en-US/component/collapse.html
• WAI-ARIA accordion guidance expects header buttons to expose expanded state and control their associated panels: https://www.w3.org/WAI/ARIA/apg/patterns/accordion/

Validation

• npm ci
• npx prettier --write packages/ui/src/components/navigation/Collapse/Collapse.tsx packages/ui/src/components/navigation/Collapse/Collapse.test.tsx docs/components/collapse.md
• npm run lint:ui
• npm run typecheck:ui
• npm run test:ui (24 files, 74 tests)
• npm run build:ui
• npm run build

Notes

• npm ci still reports existing Node 23 engine warnings and existing npm audit findings (1 low, 4 moderate, 2 high).
• npm run build still reports existing Browserslist and VitePress chunk-size warnings.

[ecc-tools]

ECC bundle files are already tracked in this repository. Skipping generation of another bundle PR.