feat: add PostgreSQL schema isolation for playground environment

- Create schema.rs utility module with table_name() function
- Add schema prefix to all SQL queries in postgres_db.rs
- Support dev schema for playground, public for production
- Add DATABASE_SCHEMA, MONGODB_DATABASE, QDRANT_COLLECTION config
- Fix 40+ functions including videos, chunks, frames, vectors, etc.
- Update Cargo dependencies

src/core/db/mod.rs

@@ -1,6 +1,8 @@
 use anyhow::Result;
 use async_trait::async_trait;
 
+pub mod schema;
+
 use crate::core::chunk::Chunk;
 
 #[derive(Debug, Clone)]