Restructure into backend/ and frontend/ subprojects

- backend/ uses proper Python src layout (src/media_library_viewer_api/)
  with pyproject.toml, hatchling build, and PYTHONPATH=src convention
- frontend/ is a Vite + React + TypeScript SPA
- archive/ preserves the original Streamlit prototype for reference
- Cleaned up root to only contain docs, license, and subproject dirs
- Updated README for the new dual-subproject architecture

archive/src/media_library_viewer/config.py

@@ -0,0 +1,49 @@
+"""Configuration loading for the app.
+
+Configuration is intentionally environment/.env based so credentials stay out of
+source control and the same package can be reused by different frontends or
+process managers.
+"""
+
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+@dataclass(frozen=True)
+class JellyfinConfig:
+    """Jellyfin connection settings."""
+
+    url: str = os.getenv("JELLYFIN_URL", "")
+    api_key: str = os.getenv("JELLYFIN_API_KEY", "")
+    user_id: str = os.getenv("JELLYFIN_USER_ID", "")
+
+
+@dataclass(frozen=True)
+class SSHConfig:
+    """SSH connection settings for remote file/resource access."""
+
+    host: str = os.getenv("SSH_HOST", "")
+    username: str = os.getenv("SSH_USERNAME", "")
+    port: int = int(os.getenv("SSH_PORT", "22"))
+    key_filename: str = os.getenv("SSH_KEY_FILENAME", str(Path.home() / ".ssh" / "id_rsa"))
+    password: str = os.getenv("SSH_PASSWORD", "")
+    media_root: str = os.getenv("REMOTE_MEDIA_ROOT", "")
+    path_prefix: str = os.getenv("REMOTE_PATH_PREFIX", "")
+
+
+@dataclass(frozen=True)
+class AppConfig:
+    jellyfin: JellyfinConfig = JellyfinConfig()
+    ssh: SSHConfig = SSHConfig()
+
+
+def load_config() -> AppConfig:
+    """Build an AppConfig snapshot from the current environment/.env file."""
+    return AppConfig()