Phase 2 Part 2: Fix Rust compilation errors after rename

Fixed all compilation errors resulting from the crate rename:

- Fixed FunctionCallOutputPayload::from() double reference issue in response_processing.rs:61
  - Removed unnecessary & as call_tool_result was already a reference
- Fixed spawn_task method call in llmx.rs by adding & reference to Arc<Session>
- Fixed Arc type inference by adding explicit type annotations
- Fixed tokio::join! type inference by separating future creation
- Updated all remaining crate::codex imports to crate::llmx across:
  - tools/orchestrator.rs
  - tools/handlers/shell.rs
  - apply_patch.rs
  - compact.rs
  - unified_exec/mod.rs
  - tools/context.rs
  - tools/sandboxing.rs
  - tools/events.rs

Successfully verified with cargo check --bin llmx (31.50s compile time).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

llmx-rs/core/src/tasks/compact.rs

@@ -3,7 +3,7 @@ use std::sync::Arc;
 use async_trait::async_trait;
 use tokio_util::sync::CancellationToken;
 
-use crate::codex::TurnContext;
+use crate::llmx::TurnContext;
 use crate::compact;
 use crate::state::TaskKind;
 use llmx_protocol::user_input::UserInput;