feat(03-04): add CodeWhisperer, Replit AI, Codestral, watsonx, Oracle AI providers

- Codestral with low-confidence 32-char generic pattern + high entropy
- watsonx with IBM IAM token endpoint for verification
- CodeWhisperer, Replit AI, Oracle AI as keyword-only
- Completes PROV-07 (10 Tier 7 code/dev tools providers)

pkg/providers/definitions/watsonx.yaml

@@ -0,0 +1,18 @@
+format_version: 1
+name: watsonx
+display_name: IBM watsonx
+tier: 7
+last_verified: "2026-04-05"
+keywords:
+  - "watsonx"
+  - "WATSONX_API_KEY"
+  - "WATSONX_PROJECT_ID"
+  - "IBM_CLOUD_API_KEY"
+  - "us-south.ml.cloud.ibm.com"
+  - "watsonx.ai"
+verify:
+  method: POST
+  url: https://iam.cloud.ibm.com/identity/token
+  headers: {}
+  valid_status: [200]
+  invalid_status: [400, 401]