Build/verify bundled aether resource

[Nishef1]

Summary

Fail the build early when the Aether executable is missing/empty or when the Tauri resource configuration no longer includes the binaries directory.

Problem

A desktop bundle can otherwise progress into packaging with a broken core-resource setup and only fail later on a clean machine, where the application cannot resolve the bundled Aether binary.

Because the release workflow already fetches the core before packaging, this is a natural point to assert the packaging contract explicitly.

Changes

• add scripts/verify-bundled-aether.mjs
• verify the platform-appropriate core exists (aether.exe on Windows, aether elsewhere)
• verify the core is a non-empty file
• parse src-tauri/tauri.conf.json and verify bundle.resources contains binaries/*
• expose the check as npm run verify:bundled-aether
• run the check in the build workflow immediately after core preparation and before packaging

Why

This converts a clean-machine runtime failure into a deterministic build-time failure with a direct error message. It also guards against accidental changes to the Tauri resource glob that would silently stop shipping the core.

Scope

This PR only validates the existing bundled-core contract. It does not change how the core is downloaded, selected, executed, or updated.

Validation

• compared against upstream main at 9ba2ef0: three focused files changed
• node --check scripts/verify-bundled-aether.mjs: passed in an equivalent fixture
• functional fixture with a non-empty platform core plus bundle.resources: ["binaries/*"]: passed
• manually reviewed the failure conditions for missing/empty core and missing resource glob

The full repository checks were not executable from the connector environment. Also note that this branch independently touches build.yml; if the Windows fetch-helper PR merges first, rebase this branch onto the new upstream main before submitting/merging it.