feat(cli): Display confidence level in findings output

[dcramer]

Add confidence level display to findings in CLI output

When triaging findings, severity alone doesn't tell the full story. A high-severity finding with low confidence needs very different treatment than one with high confidence. This surfaces confidence as a color-coded badge (green/yellow/red) after the description in both TTY output and the interactive fix flow, so users can make better triage decisions at a glance.

Badge is omitted entirely when confidence is undefined, keeping output clean for skills that don't report it.

┌── security-review ──────────────────────── [4.2s] ──┐
│ 1 finding: ● 1 high                                 │
├──────────────────────────────────────────────────────┤
│                                                      │
│ ● (high) SQL injection risk in query builder         │
│   src/api/auth.ts:42  +0.8s                          │
│   42 │ const query = buildQuery(userId);              │
│                                                      │
│   User input is interpolated into a SQL query...     │
│                                                      │
│   [high confidence]                                  │
│                                                      │
│   Suggested fix:                                     │
│   - const query = buildQuery(userId);                │
│   + const query = buildQuery(sanitize(userId));      │
│                                                      │
└──────────────────────────────────────────────────────┘

Closes #190

[cursor]

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