[codex] release v1.5.11 - #335

What changed

• Bump all six required macOS/Windows release version sources from 1.5.10 to 1.5.11.
• Update version-bound macOS and Windows regression fixtures.
• Document the shared Codex 26.727 Settings marker fix included from main commit 6e71534cd9cd55f87d1f6c9ff1cf305c7ef43893.

Local validation

• Six-source version consistency: all exactly 1.5.11.
• Portable Node regressions: 82/82 passed (macOS 63, Windows 19).
• macOS and Windows payload checks: passed and report v1.5.11.
• Shared runtime asset sync: passed.
• Complete applicable macOS suite: passed; only documented full-Xcode, installed signed-runtime, and Doctor branches skipped.
• git diff --check: passed.

Release gate

Merge only after all four exact-head CI jobs pass. The repository Release workflow must then build and publish the tag, DMG, Setup.exe, and SHA256SUMS.txt from the exact resulting main commit.

After publication, install the public assets on current Codex 26.727 for both platforms and verify Home, an existing thread, Settings General/Appearance, restart persistence, full community Safe CSS themes, and same-ID ZIP replacement. Do not close #318, #320, #322, or #326 until those public dual-platform checks pass.