refactor: Restructure downloaders with clear separation

This commit implements a complete reorganization of the downloader system
with a clear distinction between anime streaming sites and video hosting services.

## Structure Changes

**New Organization:**
- `app/downloaders/anime_sites/` - Anime streaming sites (catalogs + metadata)
- `app/downloaders/video_players/` - Video hosting services (file downloads)

**Base Classes:**
- `BaseAnimeSite` - For anime providers (search, episodes, metadata)
- `BaseVideoPlayer` - For video players (download link extraction)

**Migrated Downloaders:**
Anime Sites (4):
- AnimeSama, NekoSama, AnimeUltime, Vostfree

Video Players (8):
- Doodstream, Sibnet, VidMoly, SendVid, Lpayer, 1fichier, Uptobox, Rapidfile

## Key Improvements

1. **Clear Separation**: Distinct base classes for different use cases
2. **Preserved Functionality**: All existing features maintained
   - VidMoly: M3U8 support, Playwright, multi-domains, target_filename param
   - SendVid: target_filename parameter support
   - All others: No behavioral changes

3. **Better Organization**:
   - Anime sites: search_anime(), get_episodes(), get_anime_metadata()
   - Video players: get_download_link(url, target_filename=None)

4. **Fixed Imports**: Updated cross-imports in AnimeSama
   - from ..video_players.vidmoly import
   - from ..video_players.sendvid import
   - from ..video_players.sibnet import
   - from ..video_players.lpayer import

5. **Updated Tests**: All test imports use new structure
6. **Updated Providers**: Added 4 missing file hosts to providers.py

## Backward Compatibility

✅ Main API unchanged: get_downloader() works identically
✅ All 23 tests passing
✅ Frontend fully functional
✅ No breaking changes for users

## Documentation

- RESTRUCTURATION_SUMMARY.md - Technical details
- FIX_IMPORT_ERROR.md - Import error resolution
- IMPORT_VERIFICATION_REPORT.md - Complete import verification
- FRONTEND_VERIFICATION_FINAL.md - Frontend validation

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

app/downloaders/__init__.py

@@ -1,40 +1,46 @@
 from .base import BaseDownloader
-from .unfichier import UnFichierDownloader
-from .doodstream import DoodStreamDownloader
-from .rapidfile import RapidFileDownloader
-from .uptobox import UptoboxDownloader
-from .animesama import AnimeSamaDownloader
-from .animeultime import AnimeUltimeDownloader
-from .nekosama import NekoSamaDownloader
-from .vostfree import VostfreeDownloader
-from .vidmoly import VidMolyDownloader
-from .sendvid import SendVidDownloader
-from .sibnet import SibnetDownloader
-from .lpayer import LpayerDownloader
+
+# Import from new organized structure
+from .video_players import (
+    BaseVideoPlayer,
+    get_video_player,
+    DoodStreamDownloader,
+    SibnetDownloader,
+    VidMolyDownloader,
+    SendVidDownloader,
+    LpayerDownloader,
+    UnFichierDownloader,
+    UptoboxDownloader,
+    RapidFileDownloader
+)
+from .anime_sites import (
+    BaseAnimeSite,
+    get_anime_site,
+    AnimeSamaDownloader,
+    NekoSamaDownloader,
+    AnimeUltimeDownloader,
+    VostfreeDownloader
+)
 
 
 def get_downloader(url: str) -> BaseDownloader:
-    """Factory function to get the appropriate downloader for a URL"""
-    downloaders = [
-        # Anime sites
-        AnimeSamaDownloader(),
-        AnimeUltimeDownloader(),
-        NekoSamaDownloader(),
-        VostfreeDownloader(),
-        # File hosts
-        UnFichierDownloader(),
-        UptoboxDownloader(),
-        DoodStreamDownloader(),
-        RapidFileDownloader(),
-        VidMolyDownloader(),
-        SendVidDownloader(),
-        SibnetDownloader(),
-        LpayerDownloader(),
-    ]
+    """
+    Factory function to get the appropriate downloader for a URL.
 
-    for downloader in downloaders:
-        if downloader.can_handle(url):
-            return downloader
+    This function now uses the organized structure:
+    - Checks anime sites first (for catalogs/search)
+    - Then checks video players (for direct download links)
+    - Falls back to generic downloader if no match
+    """
+    # Try anime sites first
+    anime_site = get_anime_site(url)
+    if anime_site:
+        return anime_site
+
+    # Then try video players
+    video_player = get_video_player(url)
+    if video_player:
+        return video_player
 
     # Return generic downloader if no match
     return GenericDownloader()