feat: Add AGENTS.md and new downloaders with metadata enrichment

- Add AGENTS.md for agentic coding guidelines
- Add Oneupload and Smoothpre video player downloaders
- Add MetadataEnrichment service with Kitsu API fallback
- Add tests for metadata enrichment and provider detection
- Update .gitignore to ignore runtime config files

AGENTS.md

@@ -0,0 +1,182 @@
+# AGENTS.md - Agentic Coding Guidelines
+
+This file provides guidance for AI agents working in this repository.
+
+## Quick Start
+
+```bash
+# Setup
+python3 -m venv venv && source venv/bin/activate
+pip install -r requirements.txt
+
+# Run dev server
+uvicorn main:app --reload --host 0.0.0.0 --port 3000
+```
+
+## Build, Lint & Test Commands
+
+### Running Tests
+
+```bash
+# All tests
+pytest
+
+# With coverage
+pytest --cov=app --cov-report=html
+
+# Unit only (fast)
+pytest -m "unit"
+
+# Exclude slow tests
+pytest -m "not slow"
+
+# Verbose with print debugging
+pytest -v -s
+```
+
+### Running Single Tests
+
+```bash
+# Specific file
+pytest tests/test_sonarr.py -v
+
+# Specific class
+pytest tests/test_sonarr.py::TestSonarrHandler -v
+
+# Specific test
+pytest tests/test_sonarr.py::TestSonarrHandler::test_add_mapping -v
+
+# Pattern match
+pytest -k "test_download" -v
+```
+
+## Code Style
+
+### Imports (PEP 8 order)
+1. Standard library (`os`, `json`, `asyncio`)
+2. Third-party (`httpx`, `beautifulsoup4`, `fastapi`)
+3. Local app (`app.config`, `app.utils`)
+
+```python
+import os
+import asyncio
+from typing import Optional
+
+import httpx
+from fastapi import APIRouter, HTTPException
+
+from app.config import get_settings
+from app.models import DownloadTask, DownloadStatus
+```
+
+### Formatting
+- **Line length**: 120 chars max
+- **Indentation**: 4 spaces
+- **Blank lines**: 2 between top-level, 1 between inline
+
+### Type Annotations
+- Use explicit types
+- Use `Optional[X]` not `X | None`
+- Use `list[X]`, `dict[X, Y]`
+
+```python
+# Good
+async def get_download_link(url: str, target_filename: Optional[str] = None) -> tuple[str, str]:
+    results: list[dict[str, str]] = []
+
+# Avoid
+async def get_download_link(url, target_filename=None):
+    results = []
+```
+
+### Naming Conventions
+
+| Element | Convention | Example |
+|---------|------------|---------|
+| Modules | snake_case | `download_manager.py` |
+| Classes | PascalCase | `DownloadManager` |
+| Functions | snake_case | `get_download_link()` |
+| Constants | UPPER_SNAKE | `MAX_PARALLEL_DOWNLOADS` |
+| Variables | snake_case | `download_task` |
+| Enums | PascalCase | `DownloadStatus` |
+| Enum values | UPPER_SNAKE | `DownloadStatus.PENDING` |
+
+### Async/Await
+- Always use for I/O operations
+- Close clients properly to avoid leaks
+
+```python
+async def close(self):
+    await self.client.aclose()
+```
+
+### Error Handling
+- Use try/except for recoverable errors
+- Raise specific exceptions (`HTTPException`, `ValueError`)
+- Never use empty except blocks
+- Log errors appropriately
+
+```python
+try:
+    result = await client.get(url)
+except httpx.TimeoutException:
+    logger.warning(f"Request timeout for {url}")
+    raise HTTPException(status_code=504, detail="Request timeout")
+```
+
+### File Operations
+- Always sanitize filenames: `app.utils.sanitize_filename()`
+- Validate paths: `app.utils.is_safe_filename()`
+
+### Testing
+- Use pytest with pytest-asyncio
+- Mark tests: `@pytest.mark.unit`, `@pytest.mark.integration`
+- Use fixtures from `tests/conftest.py`
+
+```python
+@pytest.mark.unit
+@pytest.mark.asyncio
+async def test_download_manager():
+    manager = DownloadManager(max_parallel=3)
+    assert manager.max_parallel == 3
+```
+
+### Security
+- Never hardcode secrets - use environment variables
+- Validate all inputs (URLs, filenames)
+- Use HMAC for webhook verification when configured
+- Limit CORS origins - never use `*` in production
+
+## Architecture Patterns
+
+**Three-Tier Downloader:**
+1. `app/downloaders/anime_sites/` - Anime catalogs
+2. `app/downloaders/series_sites/` - TV series catalogs  
+3. `app/downloaders/video_players/` - File hosting
+
+Each has base class and factory. When adding providers:
+1. Inherit from appropriate base class
+2. Implement required methods
+3. Register in factory
+4. Add to providers config in `app/providers.py`
+
+**URL Convention**: Pipe-separated format preserves metadata:
+```
+video_url|anime_page_url|episode_title
+```
+
+## Key Files
+
+| File | Purpose |
+|------|---------|
+| `main.py` | FastAPI app, endpoints |
+| `app/config.py` | Pydantic Settings |
+| `app/download_manager.py` | Download queue |
+| `app/utils.py` | sanitize_filename |
+| `app/auth.py` | JWT auth |
+| `app/models/__init__.py` | Pydantic models |
+
+## Configuration
+
+- Use `.env` from `.env.example`
+- JWT_SECRET_KEY must change in production