feat(code): CLI client with gRPC connection + local tools

phase 3 client core:
- sunbeam code subcommand with project discovery, config loading
- gRPC client connects to Sol, starts bidirectional session
- 7 client-side tool executors: file_read, file_write, search_replace,
  grep, bash, list_directory
- project context: .sunbeam/prompt.md, .sunbeam/config.toml, git info
- tool permission config (always/ask/never per tool)
- simple stdin loop (ratatui TUI in phase 4)
- aligned sunbeam-proto to tonic 0.14

sunbeam-proto/Cargo.toml

@@ -5,8 +5,10 @@ edition = "2024"
 description = "Shared protobuf definitions for Sunbeam gRPC services"
 
 [dependencies]
-tonic = "0.13"
-prost = "0.13"
+tonic = "0.14"
+tonic-prost = "0.14"
+prost = "0.14"
 
 [build-dependencies]
-tonic-build = "0.13"
+tonic-build = "0.14"
+tonic-prost-build = "0.14"

sunbeam-proto/build.rs

@@ -1,4 +1,4 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    tonic_build::compile_protos("proto/code.proto")?;
+    tonic_prost_build::compile_protos("proto/code.proto")?;
     Ok(())
 }