v0.3.0

Proxy Auto-Config (PAC) support (#50)

• New global CLI option --proxy-config-url (env FRONTIER_PROXY_CONFIG_URL)
  and new pd_cds_api.ApiClientState field proxy_config_url. The value is
  passed to the native client as the Frontier proxyconfigurl connection
  string keyword, so fn-fileget fetches a PAC file and lets its
  FindProxyForURL function choose the proxy per query. Accepted values:
  auto, none, or an http:///file:// URL; anything else is rejected
  before the native client runs.
• Default behavior change: the default is now auto, i.e. PAC discovery
  via WPAD (http://wpad/wpad.dat). Proxies returned by the PAC file take
  priority; --cache-proxy-url is still sent and drops to backup priority.
• Migration: if no PAC is reachable, fn-fileget fails with a fatal
  configuration error (there is no silent fallback). On networks without a
  WPAD-served PAC, restore previous behavior with
  --proxy-config-url none / FRONTIER_PROXY_CONFIG_URL=none, or point the
  option at a site-provided PAC file, e.g.
  http://wlcg-wpad.fnal.gov/wpad.dat.
• Details: CLI guide — Proxy auto-config.

Also in this release

• Release process: a merge to main publishes a GitHub Release only when
  VERSION changed, so rebuilt wheels can no longer clobber the digests the
  live /simple/ index pins (#44).
• Release notes for GitHub Releases are now generated from merged PR commit
  subjects, with a docs Release-history page and DUNE-branded site theming
  (#47).
• The published wheel index is smoke-tested automatically after every release
  deploy and weekly, verifying installability and digest integrity (#41).