fix(injector): verify injection via module list, not truncated thread exit code

[xxxnpno]

Problem

inject_dll() used GetExitCodeThread(...) != 0 as the success oracle. A thread exit code is a DWORD — only the low 32 bits of LoadLibraryW's HMODULE. A module whose load base is 4 GiB-aligned (low dword 0) makes a successful injection report failure (false negative; it can't false-positive a real failure).

Fix

After the remote thread completes, confirm vmhook.dll is actually mapped into the target by scanning its module list for the DLL base name via K32EnumProcessModulesEx + K32GetModuleBaseNameW.

• Both are exported by kernel32 (the K32* psapi forwarders) → no psapi.lib; injector.exe stays statically self-contained (KERNEL32 + msvcrt only).
• The legacy exit-code test is kept only as a fallback for the rare case enumeration is unavailable (e.g. access denied) → behaviour is never worse than before.
• Buffer grows once if the target loaded modules between the two enum calls.

Validation

• Builds clean under the project -Werror mingw flags; links kernel32-only.
• End-to-end exercised by the CI injection-based integration test on the Windows JVM cells (this PR's run).

Trial-branch per policy so master stays green during validation.

🤖 Generated with Claude Code