Phase 2: Rust Workspace Transformation (Part 1)

- Renamed directory: codex-backend-openapi-models -> llmx-backend-openapi-models
- Updated all Cargo.toml files:
  - Package names: codex-* -> llmx-*
  - Library names: codex_* -> llmx_*
  - Workspace dependencies updated
- Renamed Rust source files:
  - codex*.rs -> llmx*.rs (all modules)
  - codex_conversation -> llmx_conversation
  - codex_delegate -> llmx_delegate
  - codex_message_processor -> llmx_message_processor
  - codex_tool_* -> llmx_tool_*
- Updated all Rust imports:
  - use codex_* -> use llmx_*
  - mod codex* -> mod llmx*
- Updated environment variables in code:
  - CODEX_HOME -> LLMX_HOME
  - .codex -> .llmx paths
- Updated protocol crate lib name for proper linking

Note: Some compilation errors remain (type inference issues) but all
renaming is complete. Will fix compilation in next phase.

🤖 Generated with Claude Code

llmx-rs/core/tests/suite/mod.rs

@@ -1,5 +1,5 @@
 // Aggregates all former standalone integration tests as modules.
-use codex_arg0::arg0_dispatch;
+use llmx_arg0::arg0_dispatch;
 use ctor::ctor;
 use tempfile::TempDir;
 
@@ -24,7 +24,7 @@ mod approvals;
 mod auth_refresh;
 mod cli_stream;
 mod client;
-mod codex_delegate;
+mod llmx_delegate;
 mod compact;
 mod compact_resume_fork;
 mod deprecation_notice;