refactor(security): move all database access into pkg/security/lookup

pkg/security no longer contains SQL. Every provider calls a store interface
from lookup, implemented by a procedure backend (Postgres stored procedures,
the default there) and a direct backend (dialect-driven SQL for postgres,
sqlite, mysql and mssql with configurable table and column names).

- add sectypes, lookup, lookup/{dialect,procedure,direct,backends,ddl,conformance}
- split totp and providers sub packages out of the core package
- replace SQLNames/TableNames/QueryMode with lookup.Config (see breaking_changes.md)
- direct backend now covers column/row security and API-key login
- move txsettings SQL to lookup.ApplyTxSettings; remove password.go
- move schema scripts under lookup/, add reference DDL per dialect
- add a shared conformance suite; run it on sqlite, and on Postgres in a
  podman/docker container (RESOLVESPEC_TEST_CONTAINERS=1)
- fix procedure schema bugs found on real Postgres: duplicate p_data
  parameter, JSON null arrays, expires_at timezone casts, passkey list
  GROUP BY, missing resolvespec_passkey_login; accept zone-less timestamps

pkg/security/oauth_server_test.go

@@ -19,7 +19,7 @@ import (
 func newTestOAuthServer(t *testing.T) (*OAuthServer, *DatabaseAuthenticator) {
 	t.Helper()
 	db := newDirectTestDB(t)
-	auth := NewDatabaseAuthenticatorWithOptions(db, DatabaseAuthenticatorOptions{QueryMode: ModeDirect})
+	auth := NewDatabaseAuthenticatorWithOptions(db, DatabaseAuthenticatorOptions{Lookup: directConfig})
 	srv := NewOAuthServer(OAuthServerConfig{Issuer: "https://auth.example.com", PersistCodes: true}, auth)
 	t.Cleanup(srv.Close)
 	return srv, auth