feat(python): unify sync create_index API to match async API (#2882)

## Summary

- Transitions `LanceTable` and `RemoteTable` to use the unified
`create_index()` API matching `AsyncTable`
- Deprecates `create_scalar_index()` and `create_fts_index()` with
deprecation warnings
- Adds detection logic to distinguish legacy vs new API calls
- Adds `@overload` decorators for type checker compatibility
- Adds `accelerator` parameter to IVF config classes for GPU support

**New API:**
```python
table.create_index("vec", config=IvfPq(distance_type="l2"))
table.create_index("col", config=BTree())
table.create_index("text_col", config=FTS(with_position=True))
```

**Legacy API (deprecated):**
```python
table.create_index("l2", vector_column_name="vec")  # emits DeprecationWarning
table.create_scalar_index("col", index_type="BTREE")  # deprecated
table.create_fts_index("text_col")  # deprecated
```

Fixes #2879

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

python/python/tests/test_remote_db.py

@@ -436,22 +436,25 @@ def test_table_create_indices():
         # This is a smoke-test.
         table = db.create_table("test", [{"id": 1}])
 
-        # Test create_scalar_index with custom name
-        table.create_scalar_index(
-            "id", wait_timeout=timedelta(seconds=2), name="custom_scalar_idx"
-        )
+        # Test create_scalar_index with custom name (legacy method)
+        with pytest.warns(DeprecationWarning, match="create_scalar_index"):
+            table.create_scalar_index(
+                "id", wait_timeout=timedelta(seconds=2), name="custom_scalar_idx"
+            )
 
-        # Test create_fts_index with custom name
-        table.create_fts_index(
-            "text", wait_timeout=timedelta(seconds=2), name="custom_fts_idx"
-        )
+        # Test create_fts_index with custom name (legacy method)
+        with pytest.warns(DeprecationWarning, match="create_fts_index"):
+            table.create_fts_index(
+                "text", wait_timeout=timedelta(seconds=2), name="custom_fts_idx"
+            )
 
-        # Test create_index with custom name
-        table.create_index(
-            vector_column_name="vector",
-            wait_timeout=timedelta(seconds=10),
-            name="custom_vector_idx",
-        )
+        # Test create_index with custom name (legacy form: vector_column_name kwarg)
+        with pytest.warns(DeprecationWarning, match="create_index"):
+            table.create_index(
+                vector_column_name="vector",
+                wait_timeout=timedelta(seconds=10),
+                name="custom_vector_idx",
+            )
 
         # Validate that the name parameter was passed correctly in requests
         assert len(received_requests) == 3
@@ -480,6 +483,68 @@ def test_table_create_indices():
         table.drop_index("custom_fts_idx")
 
 
+def test_remote_create_index_new_api():
+    received_requests = []
+
+    def handler(request):
+        if request.path == "/v1/table/test/create_index/":
+            content_len = int(request.headers.get("Content-Length", 0))
+            body = request.rfile.read(content_len) if content_len > 0 else b""
+            received_requests.append(json.loads(body) if body else {})
+            request.send_response(200)
+            request.end_headers()
+        elif request.path == "/v1/table/test/create/?mode=create":
+            request.send_response(200)
+            request.send_header("Content-Type", "application/json")
+            request.end_headers()
+            request.wfile.write(b"{}")
+        elif request.path == "/v1/table/test/describe/":
+            request.send_response(200)
+            request.send_header("Content-Type", "application/json")
+            request.end_headers()
+            request.wfile.write(
+                json.dumps(
+                    dict(
+                        version=1,
+                        schema=dict(
+                            fields=[
+                                dict(name="id", type={"type": "int64"}, nullable=False)
+                            ]
+                        ),
+                    )
+                ).encode()
+            )
+        else:
+            request.send_response(404)
+            request.end_headers()
+
+    from lancedb.index import BTree, FTS, IvfPq, IvfRq
+
+    with mock_lancedb_connection(handler) as db:
+        table = db.create_table("test", [{"id": 1}])
+
+        # New API: column-first, config= kwarg. Should NOT emit DeprecationWarning.
+        import warnings as _warnings
+
+        with _warnings.catch_warnings():
+            _warnings.simplefilter("error", DeprecationWarning)
+            table.create_index("vector", config=IvfPq(distance_type="l2"))
+            table.create_index("category", config=BTree())
+            table.create_index("text", config=FTS())
+            # IvfRq via new API
+            table.create_index("vector", config=IvfRq(distance_type="l2"))
+
+        # Legacy index_type="IVF_RQ" routes to IvfRq config under the hood.
+        with pytest.warns(DeprecationWarning, match="create_index"):
+            table.create_index(
+                vector_column_name="vector",
+                index_type="IVF_RQ",
+                num_partitions=8,
+            )
+
+        assert len(received_requests) == 5
+
+
 def test_table_wait_for_index_timeout():
     def handler(request):
         index_stats = dict(