Sync working tree before initial Gitea push

- File reorg: popup/options/bulk-check moved to src/ subdirs
- Shared modules: src/shared/id-extract.js, src/options/options-shared.js
- Host updates: rcjav-host.py + register/install scripts
- .gitignore expanded

host/register-host.bat

@@ -1,17 +1,10 @@
 @echo off
 REM Double-click this to register the native messaging host with Brave.
-REM Prompts for the extension ID, then runs install-host.ps1.
+REM Reads allowed extension IDs from allowed-extension-ids.json, then runs install-host.ps1.
 
 setlocal
-set /p EXT_ID="Paste the rclone-jav extension ID from brave://extensions: "
 
-if "%EXT_ID%"=="" (
-    echo No ID entered. Aborting.
-    pause
-    exit /b 1
-)
-
-powershell.exe -NoProfile -ExecutionPolicy Bypass -File "%~dp0install-host.ps1" -ExtensionId "%EXT_ID%"
+powershell.exe -NoProfile -ExecutionPolicy Bypass -File "%~dp0install-host.ps1"
 echo.
 echo Done. Press any key to close.
 pause >nul