fix: separate Files view icon setting

[vycdev2]

Summary

• add todo.file.view.icons so Files-view group icons can be configured independently from the Embedded view
• wire Files-view groups to the new setting instead of todo.embedded.view.icons
• cover both the configuration schema and production wiring

Verification

• focused RED on untouched upstream/develop failed because the independent setting was absent
• TS_NODE_TRANSPILE_ONLY=1 npx mocha --no-config -r ts-node/register test/configuration.spec.ts --exit — passed (4 tests)
• npm test — passed (135 tests)
• npm run compile — passed
• npm run format:check — passed
• git diff --check — passed

Distinctness

• Complete repository history and current fork branches were searched; no existing issue or PR adds an independent Files-view icon setting.

Risk

• Low: the new setting defaults to true, preserving the existing default appearance while decoupling the two views.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.