fix(rust/sedona): Fix panic when displaying very long content

[paleolimbot]

Fixes a panic when the content of a table is unexpectedly large. The first issue I hit this was was explain plans.

In addition to at least one issue here, there is quite a lot of unchecked addition in the underlying renderer, which we work around by truncating any u16s or strings to 32,000.

Reprex from original issue now renders without panicing:

import sedona.db

sd = sedona.db.connect()

buildings_url = (
    "s3://overturemaps-us-west-2/release/2026-01-21.0/theme=buildings/type=building/"
)

target_wkt = (
    "POLYGON ((-73.21 44.03, -73.21 43.98, -73.11 43.97, -73.12 44.03, -73.21 44.03))"
)

sd.read_parquet(
    buildings_url,
    options={"aws.skip_signature": True, "aws.region": "us-west-2"},
).to_view("buildings")

sd.sql(f"""
SELECT count(*) FROM buildings
WHERE ST_Intersects(geometry, ST_SetSRID(ST_GeomFromText('{target_wkt}'), 4326))
""").explain("extended").show()
#> ...very, very long output that does not crash

Closes #388.

[Copilot]

Pull request overview

This PR fixes a panic that occurred when displaying tables with unexpectedly large content, particularly in explain plans. The fix addresses unchecked arithmetic operations that could cause integer overflow by introducing saturating addition and conservative maximum width limits.

Changes:

• Introduced WIDTH_MAX constant (32,000) to prevent overflow in comfy table's internal arithmetic
• Replaced unchecked addition with saturating_add throughout width calculations
• Added content truncation in the cell method to limit string length to WIDTH_MAX

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[zhangfengcdt]

This seems to be limiting the character length, but not display length (width). They may not be the same or may have issues with multi-byte characters. Maybe use unicode width string handling?

[paleolimbot]

These are uniocde widths! https://doc.rust-lang.org/std/primitive.str.html#method.chars . (We also have tests for unicode output to ensure the character math works for that).

[zhangfengcdt]

Not very clear to me why "3" here? Maybe define a constant or add comments?

[paleolimbot]

There is a comment // Padding on both sides plus separator but I am happy to clarify in a follow-up if needed!