[jshvn]

What

Adopts lib v2.8.0 directory pages (katoptra/lib#28).

• UPSTREAM: https://ftp.gnu.org/gnu/ replaces PAGE_FOOT. lib builds the footer: "Mirror of https://ftp.gnu.org/gnu/. Report a problem to gnu@katoptra.org." The upstream address is text, not a link; the contact comes from HOST.
• Both workflow pins move to lib v2.8.0 (fbe4a0d). The reusable workflows did not change in this release.
• render.txt rendered against v2.8.0.
• README and CLAUDE.md describe the footer and the redraw: a change to UPSTREAM or HOST reaches every page at the next run.

The first run on v2.8.0 redraws every page once (the stamp in .state/indexed.txt.xz does not match): about 1,308 directories, two keys each, including 7 empty directories (for example paperclips/).

Test plan

• rm -rf .task/remote && task render-update && task check against v2.8.0
• CI green
• First run on v2.8.0: summary "Directory pages" about 1,308 redrawn, smoke green
• Every upstream directory answers 200 on both keys and every row agrees with the upstream listing (scripted check), footer as above