v2026-07-05.2

Other improvements:

• Bump the Stackage resolver from lts-20.9 to lts-20.26 (GHC 9.2.5 → 9.2.8), the newest snapshot compatible with purescript-0.15.15 (#322 by @thomashoneyman)
• Modernize the server build: cabal-version: 2.4, build with -Wall -Werror (with attendant cleanup in server/Main.hs), remove unused dependencies and the redundant Setup.hs (#322 by @thomashoneyman)
• Speed up CI server builds by removing the -j1 limit; runners have had 4 vCPUs and 16GB of RAM for years (#322 by @thomashoneyman)
• Serve the site and the compiled /output modules with Cache-Control: no-cache so browsers revalidate via ETag instead of heuristically caching a stale client for months after a deploy (#322 by @thomashoneyman)