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/prompt/cursor/modes/subagent.json

@@ -0,0 +1,8 @@
+{
+  "tools": [
+    "Shell", "Grep", "Delete", "WebSearch", "WebFetch", "GenerateImage",
+    "ReadLints", "EditNotebook", "TodoWrite", "StrReplace", "Write", "Read",
+    "Glob", "GetMcpTools", "FetchMcpResource", "SwitchMode",
+    "UpdateCurrentStep", "CallMcpTool", "SembleSearch", "SembleFindRelated"
+  ]
+}