tailwind v2 staging: all batch-2 page migrations (step-zero + homepage/profile/settings/leaderboard/stats)

[kokonut121]

Summary

Combines every Tailwind V2 page migration shipped so far into a single staging PR against `pfeng_dev` for full pre-production testing. After the master merges of #610 and #619 broke the live frontend, both have been reverted from `master` (commits `8ccb686` and `ee4c5de`); this PR is the consolidated replacement that lets us validate the whole batch before going to production.

Each commit is independently reviewable — see the commit list for the per-page split.

Commits in this PR

1. step-zero prerequisites — fix the silent error-flash bug at `flashesV2.ejs:15`, port form-state preservation into `views/public/signupV2.ejs`, define `views/layouts/empty.ejs` as a real bare-shell layout, delete stale root `signupV2.ejs`/`teamV2.ejs` drafts
2. homepage — `views/private/homepageV2.ejs` + `/homepage` route. Drops the bottom search widget (jQuery-MultiSelect + Bootstrap, deferred to search.ejs PR) and the AOS scroll animations
3. profile — `views/private/profileV2.ejs` + `/profile/:username` route. Two-column responsive grid; rating tracker + correct/wrong pie chart with the custom `correctwrongPlugin`; collapsed three duplicated EJS blocks for tag rendering into one forEach
4. settings — `views/private/settingsV2.ejs` + `/settings` route. Profile/Personalization/Account/Delete forms; Alpine.js for unsaved-changes alert and delete-confirm modal (replacing jQuery + Bootstrap)
5. leaderboard — `views/private/leaderboardV2.ejs` + `/leaderboard` route. Rating leaderboard 4-col grid, Rush leaderboard, Experience leaderboard; four near-identical rating tables consolidated into one forEach
6. stats — `views/private/statsV2.ejs` + `/stats/:username` route. 5 subject sections + performance/experience/rush block; five near-identical subject sections consolidated into one forEach

All legacy `.ejs` files left in tree (deletion is in the final cleanup pass per the migration plan in #609). All routes opted into V2 individually via the `expressLayouts` middleware (the global flip is also final-pass only).

Things to test on each page

Run the standard six-item checklist on each route below at both 1280px and 375px:

1. Page loads without console errors
2. No horizontal scroll on mobile, navigation collapses correctly
3. Logged-out vs. logged-in render correctly (where applicable)
4. Forms round-trip: submit known-good (success flash) AND known-bad (error flash) — confirm flashes render in V2 styling on both
5. Page-specific JS works (charts render, modals open/close, dropdowns toggle, MathJax renders)
6. View-source contains exactly one `` and one `` — catches the most likely regression mode (forgetting `expressLayouts` middleware would render a page without nav/footer or render it with both legacy and V2 chrome)

Routes to walk:

• `/homepage` — sign in fresh, confirm it lands on V2; rating Chart.js renders with 5 subject lines; contributor and admin panels render when applicable
• `/profile` and `/profile/:someoneElse` — both Chart.js charts render (rating tracker + correct/wrong pie with on-canvas % labels); hideProfile redirect still works
• `/settings` — edit a field → orange "unsaved changes" alert; submit each form individually with valid + invalid data; click Delete Account → modal opens → Cancel + Delete both work (test with a throwaway account)
• `/leaderboard` — 4 rating columns side-by-side at desktop, stacked at mobile; medal SVGs in ranks 1-3; row colors per rank; usernames link to profile
• `/stats` (your own and another user's) — 5 subject sections each render rating + global rank + collected tags + analytics + Chart.js tracker + Change Proficiency button; performance section renders correct/wrong pie + experience bar + rush stats; global ranks fill in after ~1s
• As a teacher viewing a private student's stats — V2 page should render

Known scope decisions to verify don't break expectations

• Homepage no longer has the bottom search widget — search is in the nav
• Homepage no longer has AOS scroll animations
• Settings delete modal is Alpine, not Bootstrap
• Leaderboard/profile/stats have collapsed duplicated EJS into forEach loops — output is identical, but visually compare against pre-migration if anything looks off

🤖 Generated with Claude Code