feat(documents): add document parser, service, and API routes

Why:
- Need to parse .docx/.doc files into DocumentTree + markdown
- Need API endpoints for document upload, processing, and deletion

Changes:
- Parser: .doc→.docx conversion via LibreOffice, XML-level extraction for table-heavy docs, heuristic heading detection
- Service: upload, process (delegates to chunking), delete orchestration
- Routes: POST /documents, POST /documents/{id}/process, DELETE /documents/{id}, GET /strategies

src/documents/routes.py

@@ -0,0 +1,71 @@
+"""Document and strategy API routes.
+
+Endpoints:
+  POST   /documents              Upload a .docx file
+  POST   /documents/{id}/process  Run chunking strategies (stub until Phase 2)
+  DELETE /documents/{id}          Remove document + vectors
+  GET    /strategies              List available chunking strategies
+"""
+
+from fastapi import APIRouter, File, UploadFile
+
+from src.core.exceptions import DocumentProcessingError
+from src.core.models import PaginatedResponse, StrategyName
+from src.documents.models import (
+    DeleteResponse,
+    DocumentResponse,
+    ProcessRequest,
+    ProcessResponse,
+    StrategiesResponse,
+    StrategyInfo,
+)
+from src.documents import service
+
+router = APIRouter()
+
+
+@router.post("/documents", response_model=DocumentResponse, status_code=201)
+async def upload_document(file: UploadFile = File(...)):
+    """Upload a .docx file. Parses it, stores the document tree in SQLite."""
+    if not file.filename:
+        raise DocumentProcessingError("No filename provided")
+    if not file.filename.lower().endswith((".docx", ".doc")):
+        raise DocumentProcessingError("Only .docx and .doc files are supported")
+
+    content = await file.read()
+    if not content:
+        raise DocumentProcessingError("Empty file")
+
+    doc = service.upload_document(file.filename, content)
+    return DocumentResponse(
+        id=doc["id"],
+        filename=doc["filename"],
+        paragraph_count=doc.get("paragraph_count", 0),
+        chunk_counts=doc.get("chunk_counts", {}),
+        created_at=doc["created_at"],
+    )
+
+
+@router.post("/documents/{doc_id}/process", response_model=ProcessResponse)
+async def process_document(doc_id: str, request: ProcessRequest):
+    """Run selected chunking strategies on an uploaded document.
+
+    Currently returns stub results until Phase 2 implements the strategies.
+    """
+    return service.process_document(doc_id, request)
+
+
+@router.delete("/documents/{doc_id}", response_model=DeleteResponse)
+async def delete_document(doc_id: str):
+    """Delete a document and all its chunk vectors from Qdrant."""
+    deleted = service.delete_document(doc_id)
+    return DeleteResponse(deleted=deleted, document_id=doc_id)
+
+
+@router.get("/strategies", response_model=StrategiesResponse)
+async def list_strategies():
+    """List available chunking strategies with descriptions."""
+    strategies = service.list_strategies()
+    return StrategiesResponse(
+        strategies=[StrategyInfo(**s) for s in strategies]
+    )