Load experiment from remote URL

[sverhoeven]

Fixes #158

To use requires remote URL to have CORS enabled, see https://github.com/classmodel/class-web/blob/8aaa7f869089d43a6de745bc556ae01d15caa31f/apps/class-solid/README.md#loading-experiment-from-url

1. For happy test follow instructions in collapsed section at https://github.com/classmodel/class-web/blob/8aaa7f869089d43a6de745bc556ae01d15caa31f/apps/class-solid/README.md#loading-experiment-from-url
2. For error test use bad url like http://localhost:3000/?e=http://localhost:3333/badurl or use same as 1 but with bad url like http://localhost:3000/?e=http://localhost:3001/death-valley.json
3. To test loading toast do same as test 1 and use pnpm build;pnpm start and in web browser DevTools throttle network.

When state is too big for sharable link it shows

[Copilot]

Pull request overview

This PR implements the ability to load experiments from remote URLs using the ?e=<url> query parameter, addressing issue #158. Users can now share experiments by hosting JSON files on CORS-enabled servers.

• Added URL-based experiment loading via the ?e query parameter
• Enhanced toast notifications to persist error messages with a close button
• Provided comprehensive documentation including local development setup examples

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
apps/class-solid/src/lib/state.ts	Implements loadExperimentFromUrl() function to fetch and load experiments from remote URLs, with toast-based progress feedback
apps/class-solid/src/components/ui/toast.tsx	Makes error toasts persistent and adds a close button to allow users to dismiss error messages manually
apps/class-solid/README.md	Documents the new URL loading feature with usage examples and local development instructions including CORS setup

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

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[sverhoeven]

Do we want to show the making your own link instructions always in the share dialog?

Now you only see it when state is >32k chars.
Maybe if state is small then render own link instructions in a collapsed section

[Peter9192]

Very nice!

[Peter9192]

s or e? The PR top post also says e, but the screenshot of what to do when url too long says s 😕

[Peter9192]

Seems to be consistent s everywhere except in PR description

[sverhoeven]

yep, changed my mind to store whole state (s) of app instead of just one experiment (e).