feat(cortex-hooks): extend hooks system with async, new events, and LLM prompts (#204)

- Add new HookType events: PreToolUse, PostToolUse, PostToolUseFailure,
  PermissionRequest, UserPromptSubmit, Notification, Stop, SubagentStart,
  SubagentStop, PreCompact, Setup, SessionStart, SessionEnd
- Add async execution support (async_exec flag for fire-and-forget hooks)
- Add once execution support (once flag for single-execution-per-session)
- Add tool name matcher for tool-related hooks
- Add HookStatus enum for detailed execution status tracking
- Extend HookContext with tool/agent/session context and as_env() method
- Create prompt_hook.rs for LLM-based decision hooks (PromptHook, PromptHookExecutor)
- Create session_env.rs for persistent session environment variables
- Add semaphore-based concurrency control for hook execution
- Add comprehensive tests for new functionality (32 passing tests)

This implements AGENT_5 from ORCHESTRATE/AGENT_5_HOOKS.md

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt

Cargo.lock

@@ -5,10 +5,12 @@ edition = "2021"
 description = "Hook system for Cortex CLI (formatters, post-edit actions)"
 
 [dependencies]
-tokio = { version = "1", features = ["full", "process"] }
+tokio = { version = "1", features = ["full", "process", "sync"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tracing = "0.1"
 thiserror = "1"
 glob = "0.3"
 lazy_static = "1.4"
+dirs = "5.0"
+async-trait = "0.1"