Long numbers are reducing readability

[ewjoachim]

We should probably abbreviate large numbers:

• 1 to 999: unchanged (all digits)
• 1_000 to 9_999: 1.0k to 9.9k (1 decimal digit, truncated)
• 10_000 to 999_999: 10k to 999k (no decimal digit, truncated)
• 1_000_000 and more: 1M / 10M / 100M / 1000M etc (no decimal digit, truncated, no upper limit on numbers)

Note: it's worth with long filenames:

Maybe we should show just the start and end of filenames if they're too long