Fix current Windows Codex package resolution

[awtprod]

Summary

• resolve the current Windows Codex package layout at vendor/<triple>/bin/codex.exe
• preserve compatibility with the older vendor/<triple>/codex/codex.exe layout
• recognize absolute %APPDATA%\\npm\\*.cmd launchers as npm-managed installations so the in-app Update action remains available

Root cause

The native Command Center resolver only knew the older Windows Codex package layout. Current Codex releases moved the executable into the platform package's bin directory, so T3 Code found the package but rejected its valid native runtime. The provider maintenance classifier also treated an absolute Windows npm shim as a manual installation, disabling one-click updates.

Impact

Native Windows Command Center chats can use current Codex npm installations, and Windows npm-managed Codex providers can be updated from provider settings.

Validation

• 138 focused tests across native runtime resolution, provider maintenance, update execution, adapter startup, and update UI logic
• focused lint passed
• server typecheck passed
• formatting and git diff --check passed