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/blackbox.js

@@ -0,0 +1,77 @@
+export default {
+  "id": "blackbox",
+  "alias": "blackbox",
+  "transport": {
+    "baseUrl": "https://api.blackbox.ai/chat/completions"
+  },
+  "models": [
+    {
+      "id": "gpt-4o",
+      "name": "GPT-4o"
+    },
+    {
+      "id": "gpt-4o-mini",
+      "name": "GPT-4o mini"
+    },
+    {
+      "id": "claude-sonnet-4.6",
+      "name": "Claude Sonnet 4.6"
+    },
+    {
+      "id": "claude-sonnet-4.5",
+      "name": "Claude Sonnet 4.5"
+    },
+    {
+      "id": "claude-opus-4.6",
+      "name": "Claude Opus 4.6"
+    },
+    {
+      "id": "claude-sonnet-4-6",
+      "name": "Claude Sonnet 4.6 (Legacy)"
+    },
+    {
+      "id": "claude-opus-4-6",
+      "name": "Claude Opus 4.6 (Legacy)"
+    },
+    {
+      "id": "deepseek-chat",
+      "name": "DeepSeek Chat"
+    },
+    {
+      "id": "deepseek-v3-671b",
+      "name": "DeepSeek V3 671B"
+    },
+    {
+      "id": "deepseek-r1",
+      "name": "DeepSeek R1"
+    },
+    {
+      "id": "o1",
+      "name": "OpenAI o1"
+    },
+    {
+      "id": "o3-mini",
+      "name": "OpenAI o3-mini"
+    },
+    {
+      "id": "gemini-2.5-flash",
+      "name": "Gemini 2.5 Flash"
+    },
+    {
+      "id": "gemini-3-flash-preview",
+      "name": "Gemini 3 Flash Preview"
+    },
+    {
+      "id": "qwen3-coder-plus",
+      "name": "Qwen3 Coder Plus"
+    },
+    {
+      "id": "qwen3-max",
+      "name": "Qwen3 Max"
+    },
+    {
+      "id": "qwen3-vl-plus",
+      "name": "Qwen3 VL Plus"
+    }
+  ]
+};