refactor(open-sse): P3 provider registry — split into providers/registry/{id}.js

- 100 registry files: transport + models co-located per provider (Mongoose-style)
- providers/shared.js: shared Claude headers + OS/arch helpers (deduped)
- providers/models/helpers.js: withCodexReviewModels (kept dynamic)
- providers/index.js builds PROVIDERS + PROVIDER_MODELS = old API (content byte-for-byte)
- config/providers.js + providerModels.js → barrel re-export, keep accessors + runtime helpers
- Verified: PROVIDERS/MODELS/OAuth/alias byte-for-byte, golden translator tests pass, 0 new regression

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/providers/registry/together.js

@@ -0,0 +1,35 @@
+export default {
+  "id": "together",
+  "alias": "together",
+  "transport": {
+    "baseUrl": "https://api.together.xyz/v1/chat/completions"
+  },
+  "models": [
+    {
+      "id": "meta-llama/Llama-3.3-70B-Instruct-Turbo",
+      "name": "Llama 3.3 70B Turbo"
+    },
+    {
+      "id": "deepseek-ai/DeepSeek-R1",
+      "name": "DeepSeek R1"
+    },
+    {
+      "id": "Qwen/Qwen3-235B-A22B",
+      "name": "Qwen3 235B"
+    },
+    {
+      "id": "meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8",
+      "name": "Llama 4 Maverick"
+    },
+    {
+      "id": "BAAI/bge-large-en-v1.5",
+      "name": "BGE Large EN v1.5",
+      "type": "embedding"
+    },
+    {
+      "id": "togethercomputer/m2-bert-80M-8k-retrieval",
+      "name": "M2 BERT 80M 8K",
+      "type": "embedding"
+    }
+  ]
+};