legal: close AGPL packaging gaps

Name the copyright holder, ship NOTICE with the image, serve the licence
from the panel footer on every page, and record the vendored htmx licence.

Co-authored-by: Cursor <cursoragent@cursor.com>

README.md

@@ -262,6 +262,9 @@ Optional variables (`TRUSTED_PROXY_CIDR`, rate limits, retention): see
 
 ## License
 
+Copyright © 2026 Mikhail Yenuchenko.
+
 [AGPL-3.0](LICENSE). The AGPL closes the "SaaS loophole": if you run a modified
 version as a network-accessible service, you must make the modified source
 available to its users — not only when you distribute copies of the code.
+Third-party notices: [NOTICE](NOTICE).