fix(litellm-pgvector): vendor the source instead of a remote git build context

The server's Docker/BuildKit couldn't do a git-context build of a public
github.com repo (fails with "could not read Username ... terminal prompts
disabled" — an auth-shaped error for what should be an anonymous clone).
Rather than debug that, vendor litellm-pgvector's small source tree
directly (vendor/litellm-pgvector/, see VENDORED.md for provenance/update
steps) and build from the local path.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

vendor/litellm-pgvector/config.py

@@ -0,0 +1,60 @@
+from typing import Dict, Optional
+from pydantic import BaseModel
+from pydantic_settings import BaseSettings
+
+
+class DatabaseFieldConfig(BaseModel):
+    """Configuration for database field mappings"""
+    id_field: str = "id"
+    content_field: str = "content"
+    metadata_field: str = "metadata"
+    embedding_field: str = "embedding"
+    vector_store_id_field: str = "vector_store_id"
+    created_at_field: str = "created_at"
+
+
+class EmbeddingConfig(BaseModel):
+    """Configuration for embedding generation via LiteLLM proxy"""
+    model: str = "text-embedding-ada-002"
+    base_url: str = "http://localhost:4000"  # LiteLLM proxy URL
+    api_key: str = "sk-1234"  # LiteLLM proxy API key
+    dimensions: int = 1536
+
+
+class Settings(BaseSettings):
+    """Application settings"""
+    # Database configuration
+    database_url: str = "postgresql://username:password@localhost:5432/vectordb?schema=public"
+    
+    # API configuration
+    server_api_key: str = "your-api-key-here"
+    port: int = 8000
+    host: str = "0.0.0.0"
+    
+    # Database field mappings
+    db_fields: DatabaseFieldConfig = DatabaseFieldConfig()
+    
+    # Embedding configuration
+    embedding: EmbeddingConfig = EmbeddingConfig()
+    
+    class Config:
+        env_file = ".env"
+        env_nested_delimiter = "__"
+        case_sensitive = False
+        
+        # Allow environment variables like:
+        # DB_FIELDS__ID_FIELD=custom_id
+        # EMBEDDING__MODEL=text-embedding-3-small
+        # EMBEDDING__API_BASE=https://api.openai.com/v1
+        
+    @property
+    def table_names(self) -> Dict[str, str]:
+        """Get table names"""
+        return {
+            "vector_stores": "vector_stores",
+            "embeddings": "embeddings"
+        }
+
+
+# Global settings instance
+settings = Settings()