chore: migrate desktop artifacts to R2 (PART 1)

[paustint]

Update all environments variables to be generic S3 common endpoint names (AWS) so that we can begin our migration to R2.

All data has been migrated to R2 already, and we will need to publish one more desktop release on Backblaze where the feed is updated to our new release subdomain and migrate the newly created files to R2 for that release as well.

After that, we will pause Desktop releases while we wait for users to update to our dual publisher version - prior to merging in #1793

[Copilot]

Pull request overview

This PR standardizes desktop release artifact configuration to S3-compatible AWS_*/S3_* environment variables as groundwork for migrating desktop artifacts from Backblaze B2 to Cloudflare R2, while keeping Backblaze publishing during the sunset period.

Changes:

• Replaced Backblaze-specific env vars with generic S3-compatible AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_ENDPOINT_URL, AWS_REGION, and S3_BUCKET_NAME.
• Updated the API desktop asset lookup to use the new S3-compatible configuration.
• Adjusted electron-builder publishing to point clients at a controlled “release feed” subdomain while continuing uploads to Backblaze.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
scripts/build-electron.mjs	Removes Backblaze credential fallback when generating the electron-builder .env.
libs/api-config/src/lib/env-config.ts	Replaces Backblaze env schema with generic S3-compatible vars (incl. endpoint/bucket).
electron-builder.config.js	Adds a generic publish URL for client feed + keeps Backblaze S3 publishing target.
apps/jetstream-desktop/package.json	Removes dev publish scripts that hard-coded MinIO/S3 flags.
apps/cron-tasks/src/database-backup-cron/backup.sh	Requires explicit AWS_ENDPOINT_URL and validates it.
apps/api/src/app/services/desktop-asset.service.ts	Switches desktop feed reads from Backblaze-specific env vars to generic S3-compatible ones.
apps/api/src/app/services/tests/desktop-asset.service.spec.ts.skip	Updates mocked env var names/messages (but still needs alignment fixes).
apps/api/src/app/services/tests/desktop-asset.service.spec.ts	Updates unit test env mocking/messages for the new variable names.
.github/workflows/publish-desktop-windows.yml	Updates workflow comments to reflect S3-compatible storage credentials.
.github/workflows/publish-desktop-macos.yml	Updates workflow comments to reflect S3-compatible storage credentials.
.env.example	Documents the new S3-compatible env vars for desktop release artifacts.

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[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.