Pretty-printed table output with auto-detected TTY

[vmvarela]

Description

When stdout is a TTY, format output as an aligned table with borders. When piped, stay CSV (preserving scriptability).

Examples

$ sql-pipe sales.csv 'SELECT region, SUM(amount) as total FROM orders GROUP BY region ORDER BY 2 DESC'
┌─────────┬───────────┐
│ region  │ total     │
├─────────┼───────────┤
│ AMER    │ 203100.75 │
│ EMEA    │ 142350.00 │
│ APAC    │  98210.50 │
└─────────┴───────────┘

# Piped output stays CSV — no behavior change for scripts
$ sql-pipe sales.csv 'SELECT ...' | grep AMER
AMER,203100.75

Acceptance Criteria

• When stdout is a TTY, output is formatted as an aligned table with borders
• When stdout is piped, output remains CSV (no behavior change)
• Table includes column headers
• Columns are properly aligned
• Numeric values are right-aligned
• Text values are left-aligned
• Add --table / --no-table flags for explicit control
• Handle wide tables gracefully (truncation or horizontal scrolling)
• All existing tests pass
• New tests cover TTY detection, table formatting, and piped output

Notes

• Implementation: ~200-300 lines
• Auto-detect TTY (already done for "Loaded N rows" message)
• Buffer all rows, compute column widths, print table
• Consider row limit for table mode (e.g., first 1000 rows, then switch to CSV with warning)
• Negligible binary size impact (just string formatting)

[vmvarela]

Implemented in PR #163.