1.3.0-beta5

Second cache-correctness fix from the 1.3.0-beta4 retest on
portal-master. The amended canary protocol (admin + editor +
anon) confirmed beta4's BigPipe suppression resolved scenario (a)
but surfaced a second leakage pattern: with private-cache mode on
the homepage cache keyed identically for anonymous and
authenticated requests, so whichever variant populated the cache
first was served to everyone. Root cause was on the cache-key
side: the module emitted X-LiteSpeed-Cache-Control: private but
did not tell LSWS to vary the cache entry on the session cookie.

The reporter shipped a patch and a 27-request canary confirming
the fix. beta5 lands the patch plus the obvious follow-ups.

- Response subscriber auto-appends the session cookie name to the
  X-LiteSpeed-Vary header whenever private_cache.enabled = TRUE.
  Cookie name discovered via SessionConfiguration so the fix
  needs no new config keys.
- Three new unit tests in LscacheResponseSubscriberTest cover the
  auto-append, the no-append path in public-only mode, and the
  deduplication path.
- New status report row parses CacheVary cookie= directives out
  of .htaccess and warns when they don't match the emitted
  cookies, with a copy-pasteable suggested directive.
- New docs section in docs/htaccess-gotchas.md on authenticated
  cache differentiation, with a drush ev one-liner to discover
  the session cookie name and an example IfModule LiteSpeed
  block.

Pure cache-correctness fix; no API contract changes.

CI: pipeline 821549 green (phpunit, phpcs, cspell, phpstan,
eslint, composer-lint, composer all passing).