Port Mojolicious 9.49 and stabilize Mojo::IOLoop

[fglock]

Summary

Adds PerlOnJava support for Mojolicious 9.49 and completes the runtime/compiler compatibility work tracked by #1115. No CPAN module sources are patched.

The final changes include:

• durable JVM ownership for process-pipe handles returned through lists and stored in nested argument aggregates;
• bounded 4 MiB process-pipe buffering with backpressure and complete post-exit draining;
• deterministic socket EOF and descriptor recycling;
• interrupted blocking select returning -1 with EINTR;
• completed package-alias and UNIVERSAL behavior required by core UAT;
• Perl-correct compound-assignment lvalue order and vivification on JVM and interpreter backends;
• verifier-safe implicit defer returns, safe PerlIO->import, and writable repeated $#array lvalues;
• Windows-correct raw sysopen defaults, lexical use open handling, and exact emulated mode reporting;
• a loopback Mojolicious task-board example covering HTML, JSON, timers, and chunked output.

Final validation

• Exact current head: 4d289549f (post-UAT runtime fix 9b2377b6f; current master merge 9daa1be73).
• Immutable full gate on exact current head: nice -n 10 timeout 1200 make — PASS, all five unit shards, Joni, packaging, and shadow JAR in 3m44s. Log: /tmp/issue1115_uat_regressions_4d289549f_make.log.
• Previous hosted CI run 33224975225 on c0499c80e — PASS: Ubuntu 32m43s; Windows 30m10s. Hosted CI for 4d289549f is pending; review readiness will be reconfirmed when it is green.
• Core UAT through perl_test_runner.pl: 4/4 files and 261/261 assertions PASS:
  • perl5_t/t/mro/package_aliases.t
  • perl5_t/t/mro/package_aliases_utf8.t
  • perl5_t/t/mro/isa_aliases.t
  • perl5_t/t/op/universal.t
  • Log: /tmp/issue1115_9daa1be73_core_uat.log.
• Post-UAT focused regressions: system Perl, JVM, and interpreter all PASS, 5/5 assertions for implicit defer return cleanup, PerlIO->import injection safety, and repeated $#array lvalue identity. Logs: /tmp/issue1115_9b2377b6f_system_perl_regressions.log and /tmp/issue1115_9b2377b6f_{defer,perlio,repeat}_{jvm,int}.log.
• Reported five-file UAT slice on 9b2377b6f: defer.t 25/33, caller.t 96/115, splice.t 33/34, perlio.t 38/48, and repeat.t 49/50. This restores every behavior present in the current corpus. The 11-test caller.t and 2-test splice.t differences from the supplied baseline are tests absent from the current imported corpus, not failing assertions. Log: /tmp/issue1115_uat_regressions_9b2377b6f_runner.log.
• Process-pipe post-exit drain: system Perl, JVM, and interpreter PASS; exact 65,536-byte stderr, empty stdout, child exit 0.
• Regex debug-region regression: JVM and interpreter PASS, 4/4.
• Returned lexical handle coverage: system Perl, JVM, and interpreter PASS, 4/4.
• Interrupted blocking select: system Perl, JVM, and interpreter PASS, 2/2.
• Nested process handle in IO::Select aggregate: system Perl, JVM, and interpreter PASS, 3/3.
• Socket scope/EOF guard: JVM and interpreter PASS, 35/35.
• Compound-assignment evaluation order: system Perl, JVM, and interpreter PASS, 5/5.
• Windows integration matrix: system Perl 17/17; JVM/interpreter PerlIO layers 8/8, sysopen mode 4/4, threaded in-place editing 3/3, process drain 3/3, and socket lifetime 35/35.

Framework acceptance

• Mojolicious 9.49: 109/109 files, 4,194 tests, PASS in 955 seconds. Log: /tmp/issue1115_9daa1be73_mojolicious.log.
• Catalyst::Runtime 5.90132: 199/199 supported files, 3,774/3,774 assertions, 19 skips, 9 TODOs, PASS in 2,260 elapsed seconds. Only real-fork-only t/live_fork.t is excluded. Log: /tmp/issue1115_9daa1be73_catalyst_199_correct.log.
• DBIx::Class 0.082844: 325/325 files, 43,020 tests, PASS in 1,759 wallclock seconds, including t/52leaks.t, t/storage/error.t, and t/storage/txn_scope_guard.t. Log: /tmp/issue1115_9daa1be73_dbix_class.log.
• Mojolicious task board: JVM and interpreter both PASS readiness, rendered /, /health, /api/tasks, and all three /activity chunks. Logs: /tmp/issue1115_9daa1be73_task_board_jvm_* and /tmp/issue1115_9daa1be73_task_board_interpreter_*.

Real fork/prefork servers remain outside PerlOnJava's process model and are tracked separately in #1144.

Fixes #1115.