feat(pipeline): Anthropic Batch API, source/regulation filter, cost optimization

- Add Anthropic API support to decomposition Pass 0a/0b (prompt caching, content batching)
- Add Anthropic Batch API (50% cost reduction, async 24h processing)
- Add source_filter (ILIKE on source_citation) for regulation-based filtering
- Add category_filter to Pass 0a for selective decomposition
- Add regulation_filter to control_generator for RAG scan phase filtering
  (prefix match on regulation_code — enables CE + Code Review focus)
- New API endpoints: batch-submit-0a, batch-submit-0b, batch-status, batch-process
- 83 new tests (all passing)

Cost reduction: $2,525 → ~$600-700 with all optimizations combined.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-compliance/compliance/api/control_generator_routes.py

@@ -53,6 +53,7 @@ class GenerateRequest(BaseModel):
     batch_size: int = 5
     skip_web_search: bool = False
     dry_run: bool = False
+    regulation_filter: Optional[List[str]] = None  # Only process these regulation_code prefixes
 
 
 class GenerateResponse(BaseModel):
@@ -144,6 +145,7 @@ async def start_generation(req: GenerateRequest):
         max_chunks=req.max_chunks,
         skip_web_search=req.skip_web_search,
         dry_run=req.dry_run,
+        regulation_filter=req.regulation_filter,
     )
 
     if req.dry_run: