feat: implement live task progress tracking for CLI

This commit implements the real-time progress tracking system for CLI tasks
as specified in AGENT_10_PROGRESS.md.

## Changes

### cortex-core/src/progress/ (new module)
- Added  enum for task lifecycle events
- Implemented  and  using tokio broadcast
- Added  and  types for todo list tracking
- Added  and  types for results

### cortex-tui/src/widgets/task_progress.rs (new widget)
- Implemented  for displaying task progress in TUI
- Implemented  for aggregating progress state
- Implemented  for status bar display
- Implemented  that prevents overflow when
  multiple tasks run in parallel by:
  - Limiting visible tasks
  - Using proper vertical spacing
  - Coordinating spinner animations
  - Showing overflow indicator

## Features
- Spinners with elapsed time display
- Live tool call tracking
- Todo list with status icons (○ pending, ◐ in progress, ● completed)
- Progress bar with percentage
- Parallel task overflow prevention

Author: factorydroid

Cargo.lock

@@ -21,6 +21,8 @@ tui-textarea = "0.7"
 anyhow = { workspace = true }
 futures = { workspace = true }
 tracing = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"

cortex-core/Cargo.toml

@@ -96,6 +96,7 @@ pub mod animation;
 pub mod events;
 pub mod frame_engine;
 pub mod markdown;
+pub mod progress;
 pub mod style;
 pub mod widgets;
 
@@ -109,6 +110,10 @@ pub use frame_engine::{
     DEFAULT_CHANNEL_BUFFER, DEFAULT_TICK_RATE_MS, EngineEvent, FrameEngine, FrameEngineBuilder,
     create_event_channel, create_event_channel_with_capacity,
 };
+pub use progress::{
+    ProgressEmitter, ProgressEvent, ProgressSubscriber, TaskResult, TodoItem, TodoStatus,
+    ToolResult,
+};
 pub use style::{
     BLUE, BORDER, BORDER_HIGHLIGHT, CortexStyle, GREEN, ORANGE, PINK, PURPLE, RED, SURFACE_0,
     SURFACE_1, SURFACE_2, TEXT, TEXT_DIM, TEXT_MUTED, VOID, YELLOW,