chore: fix and standardize the timetabling UI

[zepfred]

Description of the change

Description here

Checklist

Development

• The changes have been covered with tests, if necessary.
• You have a green build, with the exception of the flaky tests.
• UI and JS files are fully tested, the user interface works for all modules affected by your changes (e.g., solve and analyze buttons).
• The network calls work for all modules affected by your changes (e.g., solving a problem).
• The console messages are validated for all modules affected by your changes.

Code Review

• This pull request includes an explanatory title and description.
• The GitHub issue is linked.
• At least one other engineer has approved the changes.
• After PR is merged, inform the reporter.

[Copilot]

Pull request overview

This PR aims to standardize/fix the timetabling UI rendering across the Kotlin and Java demos by making the frontend more tolerant of Room/Timeslot references being represented as either full objects or IDs in the returned timetable JSON. It also adjusts backend JSON serialization behavior in the Spring Boot integration module.

Changes:

• Add roomMap/timeslotMap caches and an extractId() helper to normalize rendering when fields may be objects vs IDs.
• Update schedule refresh to rebuild these maps prior to rendering.
• Remove @JsonPropertyOrder from the Spring Boot integration Timetable domain class.

Reviewed changes

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

File	Description
kotlin/school-timetabling/src/main/resources/META-INF/resources/app.js	Adds ID extraction + room/timeslot lookup maps to render schedule using resolved objects.
java/school-timetabling/src/main/resources/META-INF/resources/app.js	Same UI standardization as Kotlin module.
java/spring-boot-integration/src/main/resources/static/app.js	Same UI standardization as other modules.
java/spring-boot-integration/src/main/java/org/acme/schooltimetabling/domain/Timetable.java	Removes explicit JSON property ordering that can affect identity/reference serialization.

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[triceo]

LGTM when Copilot comments are resolved.

[triceo]

LGTM when formatting fixed.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

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[triceo]

The PR will have to be rebased and the comments looked at. (Not necessarily accepted.)