Add simple hook-based event system for task automation

[bborn]

Overview

Implements a minimal event system for TaskYou that runs scripts when tasks change state. No polling required - external callers get notified immediately.

Key Event: task.blocked

The most important event for automation - fires when a task needs user input:

# ~/.config/task/hooks/task.blocked
#!/bin/bash
curl -X POST "https://your-webhook.com" \
  -d "{\"task_id\": \"$TASK_ID\", \"title\": \"$TASK_TITLE\"}"

All Events

Event	When Emitted
task.created	New task created
task.updated	Task fields changed
task.deleted	Task removed
task.started	Execution begins
task.blocked	Task needs user input
task.completed	Task finished
task.failed	Execution failed

How It Works

1. Place executable scripts in ~/.config/task/hooks/
2. Name script after event type (e.g., task.blocked)
3. Script runs automatically when event occurs

Environment variables available:

• TASK_ID, TASK_TITLE, TASK_STATUS, TASK_PROJECT
• TASK_EVENT, TASK_TIMESTAMP

Example

# Desktop notification when task needs input
cat > ~/.config/task/hooks/task.blocked << 'EOF'
#!/bin/bash
osascript -e "display notification \"$TASK_TITLE needs input\" with title \"Task Blocked\""
EOF
chmod +x ~/.config/task/hooks/task.blocked

Design

Kept it minimal:

• No HTTP/SSE server - hooks are simpler and cross-platform
• No webhook management - just put scripts in hooks dir
• No ty events watch - use ty events list for history

Net +545 lines (simplified from ~3200 in initial implementation)

Closes #853

[bborn]

Simplification Update

After review, I've dramatically simplified the events system:

Removed:

• SSE HTTP server (275 lines)
• ty events watch command
• Webhook management
• Verbose documentation

Kept:

• Simple hook-based system
• 6 essential event types: created, updated, deleted, started, completed, failed
• Environment variables passed to hook scripts

Result: Net +523 lines (was ~3200 before simplification)

The core functionality remains: scripts in ~/.config/task/hooks/ run when tasks change state. This is the simplest cross-platform solution that achieves the goal.