Play Framework

refactor: remove ServletWrapper, WAR command, and jakarta.servlet dependency (PF-78)

Drop the legacy servlet-container deployment path entirely. The marquee
features of this fork — HTTP/2 ALPN (PF-58), HTTP/3 over QUIC (PF-57),
virtual-thread dispatch via VirtualThreadScheduledExecutor — are
Netty-exclusive by design and don't function inside a servlet container,
so WAR-deployed apps were running a degraded fork. Every behavior change
also had to be implemented twice (PF-62 explicitly cites "aligning the
two transports", and PF-5 paid the same tax for security headers).

Removed
- framework/src/play/server/ServletWrapper.java (~530 lines)
- framework/test-src/play/server/ServletWrapperTest.java + HttpServletStub
- framework/pym/play/commands/war.py (the play war CLI)
- package_as_war(...) + the unused zipfile import in
  framework/pym/play/utils.py
- resources/war/web.xml (the WAR template)
- documentation/commands/cmd-war.txt (the play help war text)
- jakarta.servlet -> jakarta.servlet-api 6.0.0 in dependencies.yml
  + the corresponding framework/lib/jakarta.servlet-api-6.0.0.jar
  (pruned via ant resolve -Dprune=true)

Now-dead PF-5 servlet integration also removed
- SecurityHeadersPolicy.applyTo(HttpServletResponse, boolean) overload
  + jakarta.servlet import + class JavaDoc reference
- SecurityHeadersPlugin class JavaDoc no longer mentions ServletWrapper
- SecurityHeadersPolicyTest's two servlet test cases (servletApplyAddsHeaders,
  servletExistingHeaderNotOverwritten) and their Mockito imports

JavaDoc cleanup
- ErrorBindings: drop the @link ServletWrapper#serve500 / serve404
  reference; helper now applies only to PlayHandler error pages
- ApacheMultipartParser: drop the cosmetic javax.servlet.HttpServletRequest
  reference in the Apache Commons FileUpload citation
- PlayHandler PF-62 cookie comment no longer references ServletWrapper

Doc + skel updates
- README "Removed: WAR / servlet-container deployment" section explains
  the migration path (run via Netty, front with reverse proxy)
- application-skel/conf/application.conf rewords the http.path comment
  to reference reverse-proxy path-prefix rewriting instead of WAR mode

Breaking change
This is a SemVer-major removal for users who deployed via play war.
Affected users must switch to the embedded Netty path (play run / play
start) and front it with a reverse proxy if they need a container —
which is what most Play 1 deployments already do. The
Request.current().args.get(ServletWrapper.SERVLET_REQ) escape-hatch is
also gone; that integration was only ever populated in the WAR path,
so the same population is impacted.

Net diff: -1291 lines across 18 files. Full unit + integration test
suites green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>