Phase 1: Repository & Infrastructure Setup

- Renamed directories: codex-rs -> llmx-rs, codex-cli -> llmx-cli
- Updated package.json files:
  - Root: llmx-monorepo
  - CLI: @llmx/llmx
  - SDK: @llmx/llmx-sdk
- Updated pnpm workspace configuration
- Renamed binary: codex.js -> llmx.js
- Updated environment variables: CODEX_* -> LLMX_*
- Changed repository URLs to valknar/llmx

🤖 Generated with Claude Code

llmx-rs/core/src/function_tool.rs

@@ -0,0 +1,14 @@
+use thiserror::Error;
+
+#[derive(Debug, Error, PartialEq)]
+pub enum FunctionCallError {
+    #[error("{0}")]
+    RespondToModel(String),
+    #[error("{0}")]
+    #[allow(dead_code)] // TODO(jif) fix in a follow-up PR
+    Denied(String),
+    #[error("LocalShellCall without call_id or id")]
+    MissingLocalShellCallId,
+    #[error("Fatal error: {0}")]
+    Fatal(String),
+}