Add JsDos and Ruffle engine types

[cloud9c]

Summary

• Add jsdos and ruffle as new engine types alongside godot, unity, and custom
• Support config parsing, CLI args, init scaffolding, and dev server for both engines
• Refactor engine_type() detection to use a collected-engines pattern instead of tuple matching

Test plan

• doppler run -- cargo check compiles successfully
• doppler run -- cargo run init shows JsDos and Ruffle in the engine selection prompt
• Verify wavedash.toml with [jsdos] or [ruffle] sections parses correctly

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[calvinstudebaker]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

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