Refactor document handling and update Milvus collection settings

- Removed multiple failed document entries from `documents.json`.
- Added a new document entry with updated metadata and changed the index name to `regulations_dense_1024_v2`.
- Updated architecture documentation to reflect changes in the Milvus collection name.
- Adjusted requirements by removing the sqlalchemy dependency.
- Modified test cases to align with new document structure and naming conventions.
- Introduced a new test file for Milvus vector index runtime recovery and error handling.
- Updated assertions in various test files to ensure compatibility with the new schema.

backend/app/application/documents/services.py

@@ -508,7 +508,7 @@ class DocumentQueryService:
         """Return documents with real-time state from Milvus as the authoritative source.
 
         Algorithm:
-        1. Query Milvus for all doc metadata (doc_id, doc_name, chunk_count, …).
+        1. Query Milvus for all doc metadata (doc_id, doc_title, chunk_count, …).
         2. Load JSON/PG metadata records and index them by doc_id.
         3. Merge: Milvus-present docs get status=INDEXED and live chunk_count;
            metadata-only docs with status=INDEXED are demoted to FAILED.
@@ -536,8 +536,8 @@ class DocumentQueryService:
                 doc.chunk_count = row["chunk_count"]
                 doc.status = DocumentStatus.INDEXED
                 # Backfill fields that may be missing from older JSON records.
-                if not doc.doc_name and row.get("doc_name"):
-                    doc.doc_name = row["doc_name"]
+                if not doc.doc_name and row.get("doc_title"):
+                    doc.doc_name = row["doc_title"]
                 if not doc.regulation_type and row.get("regulation_type"):
                     doc.regulation_type = row["regulation_type"]
                 if not doc.version and row.get("version"):
@@ -553,8 +553,8 @@ class DocumentQueryService:
             if doc_id not in meta_by_id:
                 synthetic = Document(
                     doc_id=doc_id,
-                    doc_name=row.get("doc_name", doc_id),
-                    file_name=row.get("doc_name", doc_id),
+                    doc_name=row.get("doc_title", doc_id),
+                    file_name=row.get("doc_title", doc_id),
                     object_name="",
                     content_type="",
                     size_bytes=0,