feat(lsp): client-side LSP toolkit with 5 tools + integration tests

LSP client (lsp/client.rs):
- JSON-RPC framing over subprocess stdio
- Async request/response with oneshot channels
- Background read loop routing responses to pending requests
- 30s timeout per request, graceful shutdown

LSP manager (lsp/manager.rs):
- Auto-detect: Cargo.toml → rust-analyzer, package.json → tsserver,
  pyproject.toml → pyright, go.mod → gopls
- Initialize handshake, lazy textDocument/didOpen
- High-level methods: definition, references, hover, document_symbols,
  workspace_symbols
- Graceful degradation when binary not on PATH

LSP tools (tools.rs):
- lsp_definition, lsp_references, lsp_hover, lsp_diagnostics, lsp_symbols
- execute_lsp() async dispatch, is_lsp_tool() check
- All routed as ToolSide::Client in orchestrator

Tool schemas registered in Sol's build_tool_definitions() for Mistral.

Integration tests (6 new):
- Language detection for Rust project
- is_lsp_tool routing
- LSP initialize + hover on src/main.rs
- Document symbols (finds main function)
- Workspace symbols with retry (waits for rust-analyzer indexing)
- Graceful degradation with bad project path

sunbeam/Cargo.toml

@@ -33,6 +33,8 @@ tree-sitter = "0.24"
 tree-sitter-rust = "0.23"
 tree-sitter-typescript = "0.23"
 tree-sitter-python = "0.23"
+lsp-types = "0.97"
+url = "2"
 
 [dev-dependencies]
 tokio-stream = { version = "0.1", features = ["net"] }