Bootstrap node_state at DB startup to prevent hlc_high_water persistence failures

[Copilot]

On deployments where migration files are not present at runtime, replication startup reaches the HLC persist loop and repeatedly logs set_node_state key=hlc_high_water failed: db error. The failure is caused by node_state not existing when HLC state is written.

• DB startup hardening

  • Added a minimal runtime bootstrap in run_migrations() to create required table(s) before file-based migrations are loaded.
  • Current bootstrap scope is intentionally minimal: node_state only.

• Targeted bootstrap contract

  • Introduced minimal_runtime_bootstrap_sql() as the explicit source of bootstrap SQL.
  • Added a focused unit test asserting bootstrap includes CREATE TABLE IF NOT EXISTS node_state.

• Operational impact

  • HLC persistence no longer depends on migration file availability for the node_state table path.
  • Existing migration flow remains unchanged for full schema creation.

fn minimal_runtime_bootstrap_sql() -> [&'static str; 1] {
    ["CREATE TABLE IF NOT EXISTS node_state (
        key TEXT PRIMARY KEY,
        value TEXT NOT NULL
    )"]
}

fn run_migrations(client: &mut Client) {
    // ...
    bootstrap_minimal_runtime_tables(client); // ensures node_state exists
    let migrations = load_available_migrations();
    // ...
}