Release 14.6.0 into trunk

[ivan-ottinger]

Releasing new version 14.6.0.

What's Next

PR Author: Be sure to create and publish a GitHub Release pointing to trunk once this PR gets merged, copy/pasting the following text as the GitHub Release's description:

### New Features

- `upload_build_to_apps_cdn`: Update the list of valid values for `platform` to add support for `Linux - x64` and `Linux - ARM64`. [#720]

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Prepared manually rather than via bundle exec rake new_release because Ruby/Bundler isn't installed on the author's machine. The three files changed are exactly what the rake task produces: version.rb (14.5.0 → 14.6.0), CHANGELOG.md (move pending Trunk content under ## 14.6.0 and reset Trunk to empty), and Gemfile.lock (gem self-reference 14.5.0 → 14.6.0, the only line bundle install would touch on a no-dependency-change bump). Happy to re-run via the rake task if preferred — flag in review.

[ivan-ottinger]

Closing this in favor of re-opening via the standard bundle exec rake new_release flow for cleaner provenance — the manual replica was correct in shape but bypasses the documented release tooling. A new PR will follow shortly.

[ivan-ottinger]

Superseded by #722, which was generated via the standard bundle exec rake new_release flow.