refactor: workspace secrets-core + secrets-mcp MCP SaaS

- Split library (db/crypto/service) and MCP/Web/OAuth binary
- Add deploy examples and CI/docs updates

Made-with: Cursor

crates/secrets-core/src/service/mod.rs

@@ -0,0 +1,12 @@
+pub mod add;
+pub mod api_key;
+pub mod delete;
+pub mod env_map;
+pub mod export;
+pub mod get_secret;
+pub mod history;
+pub mod import;
+pub mod rollback;
+pub mod search;
+pub mod update;
+pub mod user;