Make table row counts dynamic based on terminal height

[yfarjoun]

Currently the TUI tables use hardcoded max_visible row limits (10 for running/pending, 8 for completions/stats) regardless of available terminal space. On tall terminals this wastes vertical space; on short terminals it may still be too many rows.

The row counts should adapt to the actual terminal height so tables fill the available space.

Relevant code: snakesee/tui/monitor.py — search for max_visible.