[WIP] feat: playable Win3.x and Win9.x using js-dos

[bphenriques]

draft/WIP. I need to manually review the code, the PR description and the accompanying changes ot the docs.

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Closes #3143

EmulatorJS (dosbox-pure) boots DOS games but blank-screens Windows 3.x titles. This is a known limitation that can be solved by bringing js-dos v8 (DOSBox-X backend) as a fourth in-browser player so win3x and win9x that is known to address this gap.

Related docs PR: rommapp/docs#110

Out of scope

To keep changes minimal:

• js-dos can play DOS titles, for simplicity, DOS stays on EmulatorJS only. It is a minor dos slug addition.

Changes

This PR attempts to be as similar as other external players:

• New player under frontend/src/v2/views/Player/JsDos.vue
• New Route /rom/:id/jsdos
• Admin toggle DISABLE_JSDOS
• Similar to Ruffle, the js-dos is added to the docker under /assets/jsdos, served same-origin (pinned).
• Matching defaults for better UX: autoStart: true and autoSave: true (matching EmulatorJS defaults).
• Set setNoCloud(true) as this is a self-hosted instance behind romm.

Test Plan

Writing manual tests as automated tests are covered automatically by the CI/CD (or should).

Tested titles (auto start + saves):

• Fine Artist. Saving only occurs when exiting to windows. App specific.
• Four Magic School Bus titles
• Timon & Pumba Jungle Games

Misc tests:

• Respect DISABLE_JSDOS
• Quit returns to the game list.
• The js-dos (dos.zone) cloud UI is hidden.

AI assistance disclosure

This contribution was developed with the assistance of Claude (Anthropic), an AI
coding assistant. I reviewed, tested, and validated the design, implementation,
and tests, and I take responsibility for the change.

[bphenriques]

Actions to review:

• Check save mechanism. Works manually but the exit button is not working as I expected
• Assess if I need the event handler mechanism as documented in js-dos docs. E.g., custom file storage: https://js-dos.com/save-load-game-progress.html#retrieving-current-changes

Will review later this week once my weekly limits resets. Taking a look by hand in the meantime (just slower).