feat: initialize server structure and database schema

- Added initial server setup with Cargo.toml defining dependencies and project structure.
- Created build.rs for generating protobuf bindings and validating wire contracts.
- Established database schema with initial migration files for conversations, messages, and runs.
- Introduced tools and prompts for Cursor functionality, enhancing user interaction capabilities.

server/src/model/checkpoint.rs

@@ -0,0 +1,15 @@
+//! Defines Checkpoint identity and persistence types.
+
+use std::fmt;
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[serde(transparent)]
+pub struct CheckpointId(pub i64);
+
+impl fmt::Display for CheckpointId {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(formatter)
+    }
+}