refactor: remove Slide.error from core

[leoafarias]

Summary

• remove the unused Slide.error(...) factory from superdeck_core
• delete the corresponding Slide model tests
• document the public API removal in packages/core/CHANGELOG.md

Validation

• cd packages/core && fvm exec dart test test/src/models/slide_model_test.dart test/src/models/block_model_test.dart
• cd packages/builder && fvm exec dart test test/src/parsers/section_parser_test.dart test/src/parsers/block_parser_test.dart
• rg -n "Slide\.error" /Users/leofarias/conductor/workspaces/superdeck/riyadh-v1

[docs-page]

To view this pull requests documentation preview, visit the following URL:

docs.page/btwld/superdeck~55

Documentation is deployed and generated using docs.page.

[Copilot]

Pull request overview

Removes the unused Slide.error(...) factory from superdeck_core’s Slide model, along with the corresponding tests, and documents the public API removal in the core changelog.

Changes:

• Deleted Slide.error(...) from packages/core/lib/src/models/slide_model.dart.
• Removed the Slide.error unit tests from packages/core/test/src/models/slide_model_test.dart.
• Added a changelog entry noting the API removal and directing users to DeckErrorEvent for deck loading errors.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/core/lib/src/models/slide_model.dart	Removes the Slide.error(...) factory from the Slide public API.
packages/core/test/src/models/slide_model_test.dart	Deletes tests that specifically exercised the removed factory.
packages/core/CHANGELOG.md	Documents the API removal under ## Next and points to DeckErrorEvent.

[github-actions]

Visit the preview URL for this PR (updated for commit 091cc21):

https://superdeck-dev--pr55-leoafarias-remove-sl-tg44v2rd.web.app

_{(expires Fri, 10 Apr 2026 15:17:04 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: bd68fc230762285849207e7e120aaf87cd4ca2f9}