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/flags.rs

@@ -0,0 +1,6 @@
+use env_flags::env_flags;
+
+env_flags! {
+    /// Fixture path for offline tests (see client.rs).
+    pub CODEX_RS_SSE_FIXTURE: Option<&str> = None;
+}