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/src/telemetry/service.rs

@@ -43,7 +43,7 @@ pub async fn ingest_telemetry(
         let placeholders: Vec<String> = (0..chunk.len())
             .map(|i| {
                 let base = i * cols + 1;
-                format!("(${},${},${},${},${},${},${},${},${},${},${},${},${})",
+                format!("(${},${},${},${},${},${},${},${},${},${},${},${}::timestamptz,${})",
                     base, base+1, base+2, base+3, base+4, base+5, base+6,
                     base+7, base+8, base+9, base+10, base+11, base+12)
             }).collect();