fix: display selected firmware in player

[chiyi-creator]

Summary

Fixes the firmware selector in the v2 EmulatorJS player so that the
selected firmware remains visible after selection.

The selector model stores a FirmwareSchema object, but the options were
wrapped as { title, value: firmware }. This allowed the selected firmware
to be passed to the player, but prevented RSelect from resolving and
displaying the selected item correctly.

Changes

• Pass firmware objects directly to RSelect
• Use file_name as the visible item title
• Use id as the stable item value
• Enable return-object so the player continues receiving a
  FirmwareSchema object

Testing

• npx prettier --check src/v2/views/Player/EmulatorJS.vue
• npm run typecheck
• npm test
• npm run build

Fixes #3662

AI assistance disclosure

I used ChatGPT to assist with codebase navigation, diagnosis of the
RSelect model-value mismatch, and review of the proposed fix. I manually
reviewed the final change and ran all listed checks locally.