feat(03-07): add LangSmith and 6 vector DB providers

- LangSmith with lsv2_(pt|sk) high-confidence regex
- Pinecone with pcsk_ high-confidence regex
- Weaviate, Qdrant, Chroma, Milvus/Zilliz, Neon (keyword-only)
- Completes 15 Tier 6 emerging/niche providers (PROV-06)

providers/neon.yaml

@@ -0,0 +1,19 @@
+format_version: 1
+name: neon
+display_name: Neon (Serverless Postgres + pgvector)
+tier: 6
+last_verified: "2026-04-05"
+keywords:
+  - "neon-db"
+  - "neondb"
+  - "NEON_API_KEY"
+  - "NEON_CONNECTION_STRING"
+  - "console.neon.tech"
+  - "pg.neon.tech"
+verify:
+  method: GET
+  url: https://console.neon.tech/api/v2/projects
+  headers:
+    Authorization: "Bearer {KEY}"
+  valid_status: [200]
+  invalid_status: [401, 403]