fix(build): ship the binary as wowlet, not feather

The CMake target keeps its upstream name so the twenty-odd target_* calls stay
put, but OUTPUT_NAME now produces build/bin/wowlet, and on macOS a wowlet.app
whose CFBundleExecutable matches it.

Linux and Windows already renamed the artifact as they copied it, so their cp
lines just move to the new path. macOS copied the whole bundle instead, so it
shipped Contents/MacOS/feather with a Feather name in the Info.plist, which is
what anyone installing it actually saw. The Linux install rules had the same
problem one level down: they installed feather.desktop, which sets Exec=feather
and Name=Feather Wallet, while the correct wowlet.desktop sat unused beside it.

CFBundleIdentifier moves to org.wownero.wowlet. Nothing in signing or
notarization reads it, but macOS keys per-app state by bundle id, so an existing
install starts with fresh window state.

.gitea/workflows/build-windows.yml

@@ -129,7 +129,7 @@ jobs:
         # archive contains the signed binary.
         run: |
           mkdir -p stage/tor
-          cp build/bin/feather.exe stage/wowlet.exe
+          cp build/bin/wowlet.exe stage/wowlet.exe
           cp "contrib/depends/$HOST/Tor/tor.exe" stage/tor/tor.exe
           (cp LICENSE stage/LICENSE.txt 2>/dev/null || cp COPYING stage/LICENSE.txt 2>/dev/null) || true
           ls -la stage stage/tor