FUTURE: deprecation of previous tool & forwarding

[CBrigl]

I agree we should do this, but I thought about it more and I think we should hold off until the new classes are accepted/published.

[berntpopp]

Prepared the deprecation + forwarding as a draft PR on the old repo: halbritter-lab/pld-progression-grouper#60.

What it does: a static, framework-independent deprecation banner in index.html (superseded-by-ChIC, keeps the old tool usable, prominent "Open ChIC →" link, no auto-redirect), a README [!WARNING] callout, and a DEPRECATION.md design record + repo-admin activation checklist. No app/chart logic touched. Verified with a production build + headless screenshots (desktop + mobile): the banner paints instantly, layers above the disclaimer modal, and doesn't overlap the header.

Left as a draft on purpose. The old repo deploys on push to main, so merging = going live. @CBrigl noted above that we should hold off until the new classes are accepted/published — so this is staged and ready, and a maintainer just marks it "Ready for review" + merges when the timing is right. The remaining repo-admin steps (description prefix, deprecated/archived topics, archive-last) are a copy-paste gh checklist in DEPRECATION.md.

[berntpopp]

Update: this is now merged and live — the deprecation banner is deployed at https://halbritter-lab.github.io/pld-progression-grouper/ (verified with headless Chromium on desktop + mobile: banner renders above the disclaimer modal, "Open ChIC →" links to the ChIC app, and the tab title/description now signal the move). Repo description prefixed [DEPRECATED] + deprecated topic added.

Two things surfaced along the way: the old github pages workflow pinned the retired ubuntu-20.04 runner (deploys were stuck queued) — fixed to ubuntu-latest in #61; and App.vue was overriding the static title/description on mount — fixed in #62.

Remaining optional step: archiving the repo (read-only). Holding on that because it would freeze the still-open pld-progression-grouper#52.