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/Cargo.toml

@@ -10,9 +10,18 @@ path = "src/main.rs"
 
 [dependencies]
 sunbeam-sdk = { path = "../sunbeam-sdk", features = ["all", "cli"] }
+sunbeam-proto = { path = "../sunbeam-proto" }
 tokio = { version = "1", features = ["full"] }
+tokio-stream = "0.1"
 clap = { version = "4", features = ["derive"] }
 chrono = "0.4"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 rustls = { version = "0.23", features = ["ring"] }
+tonic = "0.14"
+ratatui = "0.29"
+crossterm = "0.28"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+toml = "0.8"
+anyhow = "1"