Add vendor assets, fix CLI imports, make web UI bootable

- Copy Bootstrap 5, Bootstrap Icons, and html5-qrcode from stegasoo
- Fix stegasoo CLI import (cli group, not main wrapper)
- Add .gitignore and README.md
- Verified: soosef init, soosef serve, all routes, key export/import all work

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/soosef/cli.py

@@ -155,7 +155,7 @@ def stego():
 
 
 try:
-    from stegasoo.cli import main as stegasoo_cli
+    from stegasoo.cli import cli as stegasoo_cli
 
     # Re-register stegasoo commands under the 'stego' group
     for name, cmd in stegasoo_cli.commands.items():