Add GitHub ingestion - pull content from repos as source material

- GitHubIngestor class to fetch repo contents
- Support for .md, .txt, .notes, .draft files
- Method to ingest from GitHub directly into orchestrator
- Export GitHubIngestor in __init__.py

Usage:
    orch = OpusOrchestrator(book_type='fiction', genre='memoir')
    content = await orch.ingest_from_github('mrhavens/my-notes')
    await orch.run()

opus_orchestrator/orchestrator.py

@@ -1,13 +1,6 @@
 """Main Opus Orchestrator - Snowflake Method Implementation with Multiple Frameworks.
 
-Full pipeline supporting multiple story frameworks:
-- Snowflake Method (fractal expansion)
-- Three-Act Structure
-- Save the Cat (Blake Snyder)
-- Hero's Journey (Joseph Campbell)
-- Story Circle (Dan Harmon)
-- The 7-Point Plot (The Pantone)
-- Fichtean Curve
+Full pipeline supporting multiple story frameworks and GitHub ingestion.
 """
 
 import asyncio
@@ -52,6 +45,7 @@ from opus_orchestrator.schemas import (
     RawContent,
 )
 from opus_orchestrator.state import OpusState
+from opus_orchestrator.utils.github_ingest import GitHubIngestor
 
 
 class OpusOrchestrator: