fix(linux): find Windows programs running under Wine

[ayozetr]

find_processes cannot see a Proton-run game at all, so game_running is permanently false on Linux and every check that looks for the game by name silently finds nothing.

Neither of its two lookups can work for a Wine process:

• /proc/<pid>/exe resolves to the Wine preloader, not the program.
• comm holds whatever the program named its main thread, capped at 15 bytes. ARC Raiders reports GameThread.

Observed on a running game:

comm    = GameThread
exe     = wine64-preloader
cmdline = S:\common\Arc Raiders\PioneerGame\Binaries\Win64\PioneerGame.exe

So this also matches argv[0] from /proc/<pid>/cmdline, where the Windows path survives intact. Splitting that needs a basename helper that understands backslashes, since Path::file_name sees the whole Windows path as a single component on Linux.

names_match now drops a trailing .exe from both sides rather than only the query, so the Wine-hosted steam.exe matches the same query that native Steam's comm of steam matches. It also lowercases before stripping, because strip_suffix is case-sensitive and a .EXE spelling kept its suffix — a test caught that one.

Context in #8.

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