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

providers/sambanova.yaml

@@ -0,0 +1,25 @@
+format_version: 1
+name: sambanova
+display_name: SambaNova
+tier: 2
+last_verified: "2026-04-05"
+keywords:
+  - "sambanova"
+  - "sambanova.ai"
+  - "SAMBANOVA_API_KEY"
+  - "sambastudio"
+  - "api.sambanova.ai"
+patterns:
+  - regex: '[a-f0-9\-]{36}'
+    entropy_min: 3.5
+    confidence: low
+  - regex: '[A-Za-z0-9]{40,}'
+    entropy_min: 4.0
+    confidence: low
+verify:
+  method: GET
+  url: https://api.sambanova.ai/v1/models
+  headers:
+    Authorization: "Bearer {KEY}"
+  valid_status: [200]
+  invalid_status: [401, 403]