fix(python): check all table pages for db membership (#3395)

## Summary

- Fix `name in db` and `len(db)` for local Python connections with more
than one page of tables.
- Use `list_tables()` pagination instead of deprecated `table_names()`
with its default 10-item page.
- Add regression coverage with 20 tables so later pages are included.

Fixes #2727.

## Validation

- `python3 -m py_compile python/python/lancedb/db.py
python/python/tests/test_db.py`
- No-build Python harness that extracts and executes the edited
`LanceDBConnection` pagination methods: passed
- `uvx ruff check python/python/lancedb/db.py
python/python/tests/test_db.py`
- `uvx ruff format --check python/python/lancedb/db.py
python/python/tests/test_db.py`

Note: `uv run pytest
python/tests/test_db.py::test_db_contains_and_len_include_all_table_name_pages
-q` was attempted first, but it stayed in the broad Rust/PyO3 native
extension build and was stopped before pytest started.

python/python/tests/test_db.py

@@ -6,6 +6,7 @@ import re
 import sys
 from datetime import timedelta
 import os
+from types import SimpleNamespace
 
 import lancedb
 import numpy as np
@@ -188,6 +189,43 @@ def test_table_names(tmp_db: lancedb.DBConnection):
     assert len(result) == 3
 
 
+def test_db_contains_and_len_include_all_table_name_pages(tmp_db: lancedb.DBConnection):
+    for idx in range(20):
+        tmp_db.create_table(f"table_{idx}", data=[{"id": idx}])
+
+    assert len(tmp_db) == 20
+    for idx in range(20):
+        assert f"table_{idx}" in tmp_db
+    assert "does_not_exist" not in tmp_db
+
+
+def test_db_contains_stops_after_matching_table_page(
+    tmp_db: lancedb.DBConnection, monkeypatch
+):
+    calls = []
+    pages = {
+        None: SimpleNamespace(tables=["table_0", "table_1"], page_token="next"),
+        "next": SimpleNamespace(tables=["table_2"], page_token=None),
+    }
+
+    def list_tables(*, page_token=None, **_kwargs):
+        calls.append(page_token)
+        return pages[page_token]
+
+    monkeypatch.setattr(tmp_db, "list_tables", list_tables)
+
+    assert "table_1" in tmp_db
+    assert calls == [None]
+
+    calls.clear()
+    assert "table_2" in tmp_db
+    assert calls == [None, "next"]
+
+    calls.clear()
+    assert len(tmp_db) == 3
+    assert calls == [None, "next"]
+
+
 @pytest.mark.asyncio
 async def test_table_names_async(tmp_path):
     db = lancedb.connect(tmp_path)