feat(02-04): add Lepton, Modal, Cerebrium, Novita provider YAMLs

- Lepton AI generic-format with keyword anchors
- Modal dual token (token_id ak-, token_secret as-) medium confidence
- Cerebrium generic-format with keyword anchors
- NovitaAI with live verify endpoint (api.novita.ai/v3/openai/models)
- Dual-located in providers/ and pkg/providers/definitions/

providers/modal.yaml

@@ -0,0 +1,25 @@
+format_version: 1
+name: modal
+display_name: Modal
+tier: 2
+last_verified: "2026-04-05"
+keywords:
+  - "modal"
+  - "modal.com"
+  - "MODAL_TOKEN_ID"
+  - "MODAL_TOKEN_SECRET"
+  - "ak-"
+  - "as-"
+patterns:
+  - regex: 'ak-[A-Za-z0-9]{20,}'
+    entropy_min: 3.5
+    confidence: medium
+  - regex: 'as-[A-Za-z0-9]{20,}'
+    entropy_min: 3.5
+    confidence: medium
+verify:
+  method: GET
+  url: ""
+  headers: {}
+  valid_status: []
+  invalid_status: []