fix: cap effects tutorial interval delay

[alan747271363-art]

Summary

• cap the effects tutorial solution interval at the maximum 32-bit timer delay
• prevent repeated "slow down" clicks from overflowing the browser timer delay and making the counter tick quickly again

Closes #1954

Validation

• corepack pnpm exec prettier --write content/tutorial/01-svelte/02-reactivity/05-effects/+assets/app-b/src/lib/App.svelte
• corepack pnpm exec prettier --check content/tutorial/01-svelte/02-reactivity/05-effects/+assets/app-b/src/lib/App.svelte
• git diff --check

Note: corepack pnpm --filter svelte.dev lint still reports pre-existing formatting warnings across many unrelated files; the changed tutorial file passes the targeted Prettier check.

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