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/codestral.yaml

@@ -0,0 +1,21 @@
+format_version: 1
+name: codestral
+display_name: Codestral (Mistral Code)
+tier: 7
+last_verified: "2026-04-05"
+keywords:
+  - "codestral"
+  - "CODESTRAL_API_KEY"
+  - "codestral.mistral.ai"
+  - "codestral-latest"
+patterns:
+  - regex: '[a-zA-Z0-9]{32}'
+    entropy_min: 4.5
+    confidence: low
+verify:
+  method: GET
+  url: https://codestral.mistral.ai/v1/models
+  headers:
+    Authorization: "Bearer {KEY}"
+  valid_status: [200]
+  invalid_status: [401, 403]