# Task: Pipeline task definitions

## Goal
Create the task definition classes and registry for the pipeline orchestrator. This is Phase 1 — define what tasks exist and their metadata.

## Requirements

### Create `src/backend/services/pipeline_tasks.py`

Implement:

1. `PipelineTask` dataclass:
   - `name: str` — unique task identifier
   - `description: str` — human-readable name
   - `func: Callable` — async function to execute
   - `depends_on: list[str]` — task names that must complete first
   - `timeout: int` — max execution time in seconds
   - `retry_count: int` — number of retries on failure

2. `TaskRegistry` class:
   - `register(task: PipelineTask)` — add task to registry
   - `get(task_name: str) -> PipelineTask` — lookup task
   - `get_all() -> list[PipelineTask]` — list all registered tasks
   - `get_dependencies(task_name: str) -> list[str]` — get task dependencies
   - `get_ready_tasks( completed: set[str]) -> list[str]` — find tasks whose deps are met

3. Register built-in tasks:
   - `news_ingestion` — runs news data ingestion
   - `financials_ingestion` — runs financials data ingestion
   - `sector_rotation` — runs sector rotation analysis
   - `price_update` — runs price data update
   - `sentiment_analysis` — runs sentiment analysis

### Constraints
- File under 200 lines
- Use existing async patterns
- No real DB calls in task definitions

## Acceptance Criteria
1. `TaskRegistry` correctly tracks tasks and dependencies
2. `get_ready_tasks()` returns correct task order
3. All 5 built-in tasks are registered
4. File is under 200 lines

## Files to Create
- `src/backend/services/pipeline_tasks.py`

## Files to Read First
- `src/backend/services/news_ingestion_service.py` — existing task functions
- `src/backend/services/financials_ingestion_service.py` — existing task functions
- `src/backend/services/rotation_service.py` — existing task functions