feat: enable deep-link navigation from ExperimentSummary enter button

[gushishang]

Motivation

• Make the 进入实验 button actionable so users can open the native Physics Lab via deep links for both experiments and discussions.

Description

• Removed the disabled attribute from the entry button in src/views/ExperimentSummary.vue and added @click="goToExperiment" to the n-button element.
• Added a new goToExperiment function that maps route.params.category to either experiment or discussion, builds a physics://chinese/<type>/<id> URL, and navigates using window.location.href.

Testing

• No automated tests were run for this change; the change was committed locally (git commit) and the file modification was verified in the working tree.

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Codex Task