feat(02-04): add SambaNova, OctoAI, Friendli provider YAMLs

- SambaNova with live verify endpoint (api.sambanova.ai/v1/models)
- OctoAI generic-format with keyword anchors
- Friendli with flp_ prefix pattern (medium confidence)
- Dual-located in providers/ and pkg/providers/definitions/
- Completes PROV-02: all 14 Tier 2 providers defined

pkg/providers/definitions/octoai.yaml

@@ -0,0 +1,20 @@
+format_version: 1
+name: octoai
+display_name: OctoAI
+tier: 2
+last_verified: "2026-04-05"
+keywords:
+  - "octoai"
+  - "octo.ai"
+  - "OCTOAI_TOKEN"
+  - "OCTOAI_API_KEY"
+patterns:
+  - regex: '[A-Za-z0-9\-_\.]{40,}'
+    entropy_min: 4.0
+    confidence: low
+verify:
+  method: GET
+  url: ""
+  headers: {}
+  valid_status: []
+  invalid_status: []