feat: Windows NSIS installer, embedded icons, GUI auto-launch backend

- Add package/installer.nsi (Full/Server/Client) and toolchain.nsi
- Embed icon.ico (rounded corners) into homed.exe/waiter.exe via .syso
- GUI auto-launches homed.exe from parent dir (Windows only)
- GUI fallback connections.json from app resource dir
- Add initconfig command for config.db seeding
- Replace waiter rawmode* with raw_{unix,windows,other}.go
- Fix .gitignore: /homed instead of homed, add login.json
- Update icon.svg with rounded rect, new mascot.svg

.gitignore

@@ -1,4 +1,4 @@
-homed
+/homed
 /waiter
 *.exe
 *.log
@@ -15,6 +15,8 @@ internal/meta/
 *.hmap
 dev/
 
+login.json
+
 # GUI
 cmd/gui/node_modules/
 cmd/gui/dist/