[P2.2-T01] Add Decision enum

[RichardHightower]

Task: Add Decision enum

Phase: 2.2 - Enhanced Logging
Estimated: 0.25 day
File: cch_cli/src/models/mod.rs

Description

Create the Decision enum to represent rule evaluation outcomes in logs.

Acceptance Criteria

• Create Decision enum in models/mod.rs
• Values: Allowed, Blocked, Warned, Audited
• Implement Serialize for JSON output
• Add to log entries

Code Reference

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize)]
#[serde(rename_all = "lowercase")]
pub enum Decision {
    Allowed,
    Blocked,
    Warned,
    Audited,
}

[RichardHightower]

Completed in PR #72