Use Inertia links, paginate projects, drop unused shadcn packages

[kv4u]

Stacked on kv4u/MoveZ#2 (dashboard login), because both change the same Vue pages. Merge #2 first and GitHub retargets this PR to main.

Summary

• No more full-page reloads: internal links were plain <a> tags, so every click reloaded the whole app. They are now Inertia <Link>s.
• Projects past the first 20 are reachable: the list was paginated server-side (20 per page) but showed no page links. A new Pagination component renders Laravel's paginator links.
• Smaller bundle: removed radix-vue, class-variance-authority, clsx, tailwind-merge and lucide-vue-next. They were installed for shadcn-vue but never imported (25 packages removed).
• Test database fix: web tests could wipe a real database. phpunit.xml set DB_DATABASE=:memory: as a plain <env>, and Laravel reads $_SERVER first, so a DB_DATABASE set in the shell won. That made php artisan test run RefreshDatabase against the real database. I reproduced it with a seeded SQLite file, which was emptied. The test settings are now forced, with <server> entries added. This fix is also cherry-picked into kv4u/MoveZ#5 so it doesn't wait on Add dashboard login and per-user data scoping #2.

Test plan

• php artisan test: 39 passed. Ran it with DB_DATABASE pointing at a seeded SQLite file; afterwards the file still has 3 users and 25 projects (before the fix it was emptied).
• npm run type-check and npm run build are clean
• Playwright: 14 passed
• In the browser, signed in as the demo user with 25 projects:
  • Dashboard → Projects doesn't reload the page (a JS marker survives the navigation).
  • Page 1 shows 20 projects and page 2 shows 5, with the current page highlighted.
  • No console errors.

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