fix(lib.sh): load_state_json strict treats a missing DB table as unreadable (Issue #71)

A DB without its sessions table (or without both tables) was read as an
empty registry in strict mode, so stop closed a registered session
row-less and exited 0. Strict mode now fails on any OperationalError;
the non-strict reader is unchanged.

Refs #71

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_issue71_herdr_names.py

@@ -511,7 +511,7 @@ def test_stop_does_not_take_an_unreadable_row_for_no_row(mam_sandbox, mock_herdr
     assert "orphan74" in json.loads(Path(mock_herdr).read_text())["agents"]
 
 
-@pytest.mark.parametrize("broken", ["yaml-without-db", "db"])
+@pytest.mark.parametrize("broken", ["yaml-without-db", "db", "no-sessions-table", "no-tables"])
 def test_stop_does_not_take_an_unreadable_registry_for_no_row(mam_sandbox, mock_herdr, broken):
     """load_state_json's {} on a read error is not "no row": a registered session is not closed row-less."""
     name = "orphan75-creator-claude"
@@ -522,10 +522,18 @@ def test_stop_does_not_take_an_unreadable_registry_for_no_row(mam_sandbox, mock_
         for f in mam.glob("agent-sessions.db*"):
             f.unlink()
         (mam / "agent-sessions.yaml").write_text("herdr_sessions: [\n  - {name: " + name + "\n")
-    else:
+    elif broken == "db":
         for f in mam.glob("agent-sessions.db-*"):
             f.unlink()
         (mam / "agent-sessions.db").write_bytes(b"this is not a database" * 64)
+    else:
+        # a missing table is not an empty registry
+        conn = sqlite3.connect(str(mam / "agent-sessions.db"))
+        conn.execute("DROP TABLE sessions")
+        if broken == "no-tables":
+            conn.execute("DROP TABLE state")
+        conn.commit()
+        conn.close()
     _set_mock(mock_herdr, agents={name: _agent(mam_sandbox, "w1:p76")})
     res = _stop(mam_sandbox, name)
     assert res.returncode == 1, res.stdout + res.stderr