Bump to 1.7.0-beta.3

[Pixnop]

One line: the version becomes 1.7.0-beta.3. Everything else for the release is already on dev.

What this beta carries, for whoever reviews the release notes: the three reports from a migrating tester (custom icons now name their refusal instead of failing silently, installations can be reordered, and the launcher stops overwriting the session the game refreshed, which was turning one invalidated login into a prompt on every single launch), the per-mod update suspension a ModDB user asked for, the data folder following the typed installation name, the background selector with its repo-hosted catalog and custom image, and the reliability batch from the beta.2 test session: consent before an update downloads, a real progress bar for it, the install popup failing honestly instead of spinning forever, and image validation by signature rather than file name.

After this merges: promote to main, tag v1.7.0-beta.3, let the release workflow build the artifacts, publish the draft as a prerelease. Testers on beta.2 will be the first to see the consent prompt in action, since beta.2 still downloads updates on its own.

[Zaldaryon]

Approved. I reviewed head 9aa20ccbbf5e against dev. The diff changes only the version in package.json and package-lock.json, from 1.7.0-beta.2 to 1.7.0-beta.3. Local typecheck, lint, format check, coverage tests, unpacked build, and diff check passed: 121 files, 1,411 passed, 2 skipped. CI run 32576323795 passed typecheck, lint, test, Ubuntu, Windows, and SonarCloud. macOS is skipped by workflow policy. I found no technical issue. This approval does not authorize a merge.