feat(03-06): add Salesforce, ServiceNow, SAP, Palantir Tier 9 providers

- Keyword-only detection; strong env var anchors
- Dual-located in providers/ and pkg/providers/definitions/

pkg/providers/definitions/servicenow.yaml

@@ -0,0 +1,18 @@
+format_version: 1
+name: servicenow
+display_name: ServiceNow Now Assist
+tier: 9
+last_verified: "2026-04-05"
+keywords:
+  - "servicenow"
+  - "now-assist"
+  - "SERVICENOW_INSTANCE"
+  - "SERVICENOW_USERNAME"
+  - "SERVICENOW_PASSWORD"
+  - "service-now.com"
+verify:
+  method: GET
+  url: ""
+  headers: {}
+  valid_status: []
+  invalid_status: []