feat(03-07): add 8 emerging labs, writing tools, observability providers

- Reka, Aleph Alpha, Lamini (emerging LLM labs)
- Writer, Jasper, Typeface (writing tools)
- Comet ML/Opik, Weights & Biases (observability)
- Dual-located in providers/ and pkg/providers/definitions/

pkg/providers/definitions/reka.yaml

@@ -0,0 +1,18 @@
+format_version: 1
+name: reka
+display_name: Reka AI
+tier: 6
+last_verified: "2026-04-05"
+keywords:
+  - "reka"
+  - "REKA_API_KEY"
+  - "api.reka.ai"
+  - "reka-core"
+  - "reka-flash"
+verify:
+  method: GET
+  url: https://api.reka.ai/v1/models
+  headers:
+    X-Api-Key: "{KEY}"
+  valid_status: [200]
+  invalid_status: [401, 403]