feat: pass release notes to GitHub/GitLab release body

[asamofal]

Closes #9235

Hey! This wires the existing releaseInfo infrastructure (which already resolves releaseNotes, releaseNotesFile, and auto-detects release-notes.md) through to the GitHub and GitLab publishers. Until now that data only ended up in auto-update YAML files — the actual release drafts were always created with an empty body.

What changed

• Added releaseBody and releaseName to GithubOptions and GitlabOptions
• PublishManager.createPublisher() now resolves release info from config and injects it into publisher options (with explicit values taking precedence)
• GitHubPublisher.createRelease() passes body and name to the GitHub API
• GitlabPublisher.createRelease() uses releaseBody as description instead of the hardcoded "Release vX.Y.Z"
• Release body is truncated at 100k characters with a warning log if exceeded (addresses the size concern from the issue)
• 4 unit tests covering body, name, omission, and truncation

Resolution order for release body

1. Explicit releaseBody on publish config (new, takes precedence)
2. releaseInfo.releaseNotes from config
3. releaseInfo.releaseNotesFile read from disk
4. release-notes.md in project root (auto-detected fallback)

Config examples

// inline
{ "releaseInfo": { "releaseNotes": "## Changes\n- stuff" } }

// file reference
{ "releaseInfo": { "releaseNotesFile": "CHANGELOG.md" } }

// just drop release-notes.md in project root — auto-detected

// or override directly on publish config
{ "publish": [{ "provider": "github", "releaseBody": "custom body" }] }

Also works via CLI dot-notation: electron-builder --publish always -c.releaseInfo.releaseNotesFile=notes.md

Tested

• Unit tests pass
• Verified end-to-end against a real GitHub repo — draft release created with correct body and name

[changeset-bot]

🦋 Changeset detected

Latest commit: 1eda489

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

This PR includes changesets to release 12 packages

Name	Type
app-builder-lib	Major
electron-publish	Major
builder-util-runtime	Minor
dmg-builder	Major
electron-builder-squirrel-windows	Major
electron-builder	Major
electron-forge-maker-appimage	Major
electron-forge-maker-nsis-web	Major
electron-forge-maker-nsis	Major
electron-forge-maker-snap	Major
builder-util	Major
electron-updater	Patch

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