refactor: migrate main.py to modular routers and add project roadmap

- Migrated monolithic main.py to feature-scoped routers in app/routers/
- Added GEMINI.md for project context and AI instructional guidelines
- Updated README.md with a comprehensive modernization plan (SQL migration, robust scraping DSL, frontend modernization)
- Improved authentication with cookie support and modular JS
- Updated test suite and documentation

app/routers/router_root.py

@@ -0,0 +1,55 @@
+"""
+Root routes for Ohm Stream Downloader API.
+"""
+
+from fastapi import APIRouter
+
+from app import providers
+
+router = APIRouter(prefix="", tags=["root"])
+
+
+@router.get("/")
+async def root():
+    """Root endpoint with API information"""
+    return {
+        "message": "Ohm Stream Downloader API",
+        "status": "running",
+        "version": "2.2",
+        "endpoints": {
+            "POST /api/download": "Start a new download",
+            "GET /api/downloads": "List all downloads",
+            "GET /api/download/{task_id}": "Get download status",
+            "POST /api/download/{task_id}/pause": "Pause a download",
+            "POST /api/download/{task_id}/resume": "Resume a download",
+            "DELETE /api/download/{task_id}": "Cancel a download",
+            "GET /api/providers": "List all supported providers",
+            "GET /api/anime/search": "Search anime across all providers",
+            "GET /api/anime/metadata": "Get detailed anime metadata",
+            "GET /api/anime/episodes": "Get episode list for an anime",
+            "POST /api/anime/download-season": "Download all episodes of a season",
+            "GET /api/favorites": "List all favorite anime",
+            "POST /api/favorites": "Add anime to favorites",
+            "DELETE /api/favorites/{anime_id}": "Remove from favorites",
+            "GET /api/favorites/{anime_id}": "Get favorite anime details",
+            "GET /api/favorites/stats": "Get favorites statistics",
+            "POST /api/favorites/toggle": "Toggle anime in favorites",
+            "GET /web": "Web interface",
+        },
+    }
+
+
+@router.get("/health")
+async def health():
+    """Health check endpoint"""
+    return {"status": "healthy"}
+
+
+@router.get("/api/providers")
+async def list_providers():
+    """List all supported anime, series and file hosting providers"""
+    return {
+        "anime_providers": providers.get_anime_providers(),
+        "series_providers": providers.get_series_providers(),
+        "file_hosts": providers.get_file_hosts(),
+    }