Add folder chart command with interactive line chart

[stalep]

Features:

• Line chart of range node values plotted over domain node values
• Multi-fingerprint overlay (up to 3 series) with interactive selection
• Change detection markers: FixedThreshold, RelativeDifference, StdDevAnomaly, EDivisive with type-specific symbols and colors
• HorizontalLine for FixedThreshold min/max bounds
• Auto-detect terminal size for chart dimensions
• Braille rendering by default (unicode/ascii via --style flag)
• Alternate screen buffer for clean full-screen display
• Interactive viewport scrolling: arrow keys or h/l to scroll, Home/End to jump, q to quit
• Fingerprint selection menu when multiple fingerprints exist
• Fixed Y-axis range during scrolling for consistent visual comparison
• Centered title showing range node name and folder

Data retrieval:

• New ValueService.getChartData() method using separate recursive ancestor CTEs per node, joined in Java by root_id (~480ms vs 22s with the full getGroupedValues CTE)
• DISTINCT ON (root_id) deduplication to handle DAG fan-out through shared edges
• Sequential index X-axis (domain values may be non-numeric)