Description

The System page shows aggregate CPU% but no per-core breakdown. Add a per-core bar section to the CPU panel or as a new row between the sparkline and the process table.

Implementation:

• psutil.cpu_percent(percpu=True) returns a list of per-core percentages
• Add this call to SystemStats.sample() → "cores_pct": [...]
• Render as a grid of labeled bars: C0 [████░░░░] 42% C1 [██░░░░░░] 18% …
• Use Unicode block chars (█, ░) for bars, scaled to a fixed width (e.g. 8 chars)
• Color: green < 50%, yellow 50–80%, red > 80%
• Layout: 2 or 4 cores per row depending on terminal width / core count
• Place in the existing sys-cpu panel below the aggregate line, or as a dedicated row

Acceptance Criteria

• #1 Per-core CPU percentages shown as labeled bars
• #2 Bars are color-coded by utilization level
• #3 Layout adapts to core count (wraps to multiple rows)
• #4 Updates on same SYS_REFRESH_SECS interval as existing system stats
• #5 Fits within sys-cpu panel without requiring scroll on standard terminal widths