Fix Northstar profile paths on Proton and type checking after Flatpak builds

[TB516]

This PR was created by GPT-6

Northstar receives a Unix profile path on Linux with Proton and resolves it on the game's Windows drive. Resolve the Northstar directory with realpath() and prefix it with Z: when isProton() applies, matching the existing loader patterns. Other platforms and launch types retain their current behavior, and failures return R2Error.

Also exclude generated Flatpak directories through Quasar's extendTsConfig hook. Type checking otherwise scans thousands of bundled JavaScript files from local builds and exhausts Node's heap.

Validation:

• pnpm typecheck passes with the default heap, including after a Flatpak build.
• Existing tests: 200 passed, 5 skipped, with generated Flatpak test copies excluded.
• Built a local .flatpak; Thomas confirmed it works with the separately patched NorthstarLauncher that supports Windows absolute profile paths.

[TB516]

Quick fix with codex for the new northstar errors that we are seeing with r2. Should be accompanied by this fix in the northstar repo which allows it to load absolute paths with the -profile arg.

[TB516]

I also tossed in a change in the tsconfig to exclude the flatpak stuff which I think was missed by me initially, but it was causing my tsc to run out of memory from enumerating those files.