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/lookup/procedure/flextime.go

@@ -0,0 +1,54 @@
+package procedure
+
+import (
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+// normalizeTimes rewrites the zone-less timestamps the procedures emit (Postgres `timestamp`
+// columns serialise as "2026-01-02T03:04:05.123456") as UTC RFC 3339, so the standard
+// time.Time decoder accepts them. It handles a JSON object or an array of objects and only
+// touches string fields whose name ends in "_at" or is "expiry". Anything else, including
+// input that is not valid JSON, is returned unchanged.
+func normalizeTimes(raw []byte) []byte {
+	var v any
+	if err := json.Unmarshal(raw, &v); err != nil {
+		return raw
+	}
+	switch x := v.(type) {
+	case map[string]any:
+		fixTimes(x)
+	case []any:
+		for _, e := range x {
+			if m, ok := e.(map[string]any); ok {
+				fixTimes(m)
+			}
+		}
+	default:
+		return raw
+	}
+	out, err := json.Marshal(v)
+	if err != nil {
+		return raw
+	}
+	return out
+}
+
+func fixTimes(m map[string]any) {
+	for k, v := range m {
+		s, ok := v.(string)
+		if !ok || !(strings.HasSuffix(k, "_at") || k == "expiry") {
+			continue
+		}
+		if _, err := time.Parse(time.RFC3339Nano, s); err == nil {
+			continue
+		}
+		for _, layout := range []string{"2006-01-02T15:04:05.999999999", "2006-01-02 15:04:05.999999999"} {
+			if t, err := time.Parse(layout, s); err == nil {
+				m[k] = t.UTC().Format(time.RFC3339Nano)
+				break
+			}
+		}
+	}
+}