[FEATURE] Add interrupt/reason context to Notification hook

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The Notification hook currently fires whenever Claude waits for user input, but doesn't distinguish between:

• Natural pauses (Claude asks a question/needs clarification)
• User interrupts (ESC/Ctrl+C pressed)
• Permission requests
• Normal waiting for next command

This makes it impossible to filter notifications appropriately. Users want to be notified when Claude needs input for a question, but not when they manually interrupted Claude.

Proposed Solution

Add a reason or trigger field to the Notification hook input JSON:

{
  "hook_event_name": "Notification",
  "reason": "question" | "interrupted" | "permission" | "waiting",
  ...
}

Values:

• "question" - Claude asking for clarification/choice
• "interrupted" - User pressed ESC/Ctrl+C to interrupt
• "permission" - Claude waiting for permission approval
• "waiting" - Normal wait for next user command

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

Users running Claude in containers want audio/desktop notifications when Claude pauses with a question, but NOT when they manually interrupt execution (since they're already at the terminal).

Current workaround: None - users must accept notifications on ALL waits or disable notifications entirely.

Example Hook Configuration

{
  "hooks": {
    "Notification": [
      {
        "matcher": "*",
        "hooks": [
          {
            "type": "command",
            "command": "bash -c 'if [ \"$NOTIFICATION_REASON\" = \"question\" ]; then notify \"needs input\"; fi'"
          }
        ]
      }
    ]
  }
}

Additional Context

• Claude Code version: 2.0.28+
• This affects all notification hook use cases where interrupt vs natural pause distinction matters
• Related to existing hook events: Stop, Notification, UserPromptSubmit