feat(StudySapuri): add activity

[Neocat11]

Description

• Add a new StudySapuri activity for www.studysapuri.jp and learn.studysapuri.jp
• Show generic browsing states for the dashboard, course catalog, and My Courses pages
• Show dynamic lesson details for /topics/:topicId/lessons/:lessonNo, including course name, lesson/chapter labels, and playback timestamps while a video is playing
• Show the selected course name on /courses/:courseId
• Add localized metadata and uploaded 512x512 / thumbnail assets

Notes

• npx pmd build StudySapuri --validate passes locally when Node DNS is pointed at public resolvers in this environment
• npx eslint websites/S/StudySapuri/presence.ts passes locally
• npm run lint in this environment still hits metadata schema resolution for the remote PreMiD schema URL, so I am leaving that checklist item unchecked

Acknowledgements

• I read the Activity Guidelines
• I linted the code by running npm run lint
• The PR title follows the repo's commit conventions

Screenshots

Proof showing the creation/modification is working as expected

• Generic dashboard browsing state

• Course browsing state on /courses/:courseId

• Lesson playback state on /topics/:topicId/lessons/:lessonNo