Summary

• Add the supplied 16px outline-chevron-right artwork to the shared icon catalog, using currentColor.
• Replace the file-tree disclosure icon, pointing down when expanded and left when collapsed in RTL.

Verification

• bun run check passed (existing repository warnings only).
• bun run lint:changed origin/beta passed.
• bun test src/file/tree-model.test.ts passed (5 tests).
• Reviewed before/after captures of the real Pierre tree with production CSS; checked LTR/RTL transforms and click-to-expand.

Visual comparison

Isolated file-tree preview, LTR and RTL.

Before:

After: