Clean up unused Zemeroth demo artifacts

[YfengJ]

Closes #28.

Summary

• rename the live canvas demo from demo/zemeroth-demo to demo/human-vs-bots
• remove the unused Zemeroth engine artifacts (zemeroth.wasm, gl.js) and the unreferenced RON/font payload left with that demo folder
• remove Zemeroth-only third-party license files now that those artifacts are gone
• update the root redirect, README route/script references, and replace serve-zemeroth.sh with serve-human-vs-bots.sh

Validation

• bash -n scripts/serve-human-vs-bots.sh scripts/serve-demos.sh scripts/game-studio.sh
• test -f demo/human-vs-bots/index.html
• test ! -e demo/zemeroth-demo
• test ! -e THIRD_PARTY_ZEMEROTH_LICENSE_MIT.txt
• test ! -e THIRD_PARTY_ZEMEROTH_LICENSE_APACHE.txt
• ! rg -n "zemeroth|Zemeroth|serve-zemeroth" README.md index.html scripts demo -S
• git diff --cached --check
• served the repo with python3 -m http.server and confirmed /, /demo/human-vs-bots/, game.js, and styles.css all resolve
• ran ./scripts/serve-human-vs-bots.sh and confirmed the direct demo page serves with game.js

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.7% Duplication on New Code

See analysis details on SonarQube Cloud

[leocagli]

Thanks @YfengJ — the cleanup direction is right, but a couple of things to sort out before merging:

Scope exceeded the issue brief
The issue (#28) asked to delete zemeroth.wasm and gl.js only. This PR also renames the entire demo/zemeroth-demo/ folder to demo/human-vs-bots/ and deletes the Zemeroth license files. The rename is actually a good idea (it reflects what the folder really is), but it needs to be a conscious decision.

Merge conflict risk
PRs #30 and #31 both add/modify files under demo/zemeroth-demo/. If this merges first under the new path, those PRs will conflict and need to be rebased. We need to coordinate order.

Next steps

1. Confirm: is the folder rename intentional? If yes, we'll ask #30 and #31 to rebase against this branch before we merge this one.
2. If you want to keep the scope minimal: split into two commits — one that only deletes wasm+gl.js, and a second for the rename — so we can cherry-pick if needed.

Either way, the work looks solid. Just need alignment on scope and order.