Add BDD scenarios that capture bug #4739 — the missing TUI SQLite
session persistence layer. The cleveragents.tui.session_store module
and TuiSessionStore class do not exist; these tests verify their
absence and will pass once the implementation is in place.

All scenarios are tagged @tdd_expected_fail so CI passes while the
module is absent. The expected-fail mechanism inverts the result:
a failing AssertionError means the bug still exists (CI passes).

ISSUES CLOSED: #10879

@@ -0,0 +127,4 @@
+def step_tdd4739_get_session(context: Context, session_id: str) -> None:
+    """Assert the session record can be retrieved by its id."""
+    store = context.tdd4739_store
+    assert store is not None, "TuiSessionStore was not created"

@@ -0,0 +142,4 @@
+
+
+@then("the tdd4739 session store should list {count:d} sessions")
+def step_tdd4739_list_sessions(context: Context, count: int) -> None:

@@ -0,0 +103,4 @@
+    )
+    context.tdd4739_store = mod.TuiSessionStore(db_path=context.tdd4739_db_path)
+
+

@@ -0,0 +127,4 @@
+def step_tdd4739_get_session(context: Context, session_id: str) -> None:
+    """Assert the session record can be retrieved by its id."""
+    store = context.tdd4739_store
+    assert store is not None, "TuiSessionStore was not created"

@@ -0,0 +147,4 @@
+    store = context.tdd4739_store
+    assert store is not None, "TuiSessionStore was not created"
+    sessions = store.list_all()  # type: ignore[union-attr]
+    assert sessions is not None, "TuiSessionStore.list_all() returned None"

@@ -0,0 +108,4 @@
+@when('I save a tdd4739 session record with id "{session_id}"')
+def step_tdd4739_save_session(context: Context, session_id: str) -> None:
+    """Save a minimal session record to the store."""
+    store: typing.T.Any = context.tdd4739_store