fix(saas): Phase 5 regression fixes — SQL type casts + test data corrections

- Fix usage_stats SQL: add ::timestamptz cast for Option<String> params
- Fix usage_stats SQL: add ::bigint cast for COALESCE(SUM(...))
- Fix telemetry INSERT: add ::timestamptz cast for reported_at column
- Fix config_analysis_empty test: seed data makes total_items > 0
- Fix key_pool_crud test: key_value must be >= 20 chars
- Fix SkillManifest test helpers: add missing tools field

All 1048 tests pass: 580 Rust + 138 SaaS + 330 Desktop Vitest

crates/zclaw-saas/tests/relay_test.rs

@@ -88,7 +88,7 @@ async fn key_pool_crud() {
         post(
             &format!("/api/v1/providers/{provider_id}/keys"),
             &admin,
-            serde_json::json!({ "key_label": "Pool Key 1", "key_value": "sk-pool-key-001", "priority": 0 }),
+            serde_json::json!({ "key_label": "Pool Key 1", "key_value": "sk-pool-key-001-abcdefg", "priority": 0 }),
         ),
     ).await;
     assert_eq!(status, StatusCode::OK, "add key to pool: {body}");