feat: Provide progress updates for multiple range differential downloads

[eliotschu]

Summary of Changes

• Pass total number of expected download bytes and onProgress event emitter to multiple range differential download data splitter
• Update transferred and delta when processing downloaded part data
• After each chunk of data is handled in data splitter, check timer and emit progress message if 1s has passed, or download is complete
• Remove TODO note about this feature not being implemented

[changeset-bot]

🦋 Changeset detected

Latest commit: 0b6d9e2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
electron-updater	Minor

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[Copilot]

Pull request overview

This PR implements progress reporting for multiple range differential downloads in the electron-updater. Previously, progress events were only supported for single-range downloads (as indicated by the removed TODO comment). The implementation adds byte tracking and timed progress emission to the DataSplitter class, which handles multipart HTTP responses.

Key changes:

• Track total expected download bytes across all download ranges
• Emit progress events every 1 second during download and upon completion
• Update transferred and delta byte counters as data chunks are processed

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
multipleRangeDownloader.ts	Calculate total download bytes and pass progress callback to DataSplitter
DifferentialDownloader.ts	Remove TODO comment about missing multiple range progress support
DataSplitter.ts	Add progress tracking state, emit progress events during data processing
.changeset/three-pens-sit.md	Document the feature addition for version tracking

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[mmaietta]

This is awesome. Thanks for submitting this PR

[mmaietta]

Please address copilot comments

[eliotschu]

I have added comments for the new class properties and added a check that the divisors copilot review mentioned are truthy before attempting division.

[eliotschu]

I see that one of the tests failed. It looks like a similar failure to a couple of the linux e2e tests that failed on the last commit to master. Let me know if you think there are actually potential issues I should look into with this branch!