fix(search): show previews for commands truncated by custom columns

[ychampion]

Summary

• derive the visible command width from the configured result columns
• cover the reported custom-column layout with a preview-height regression

Why

The auto strategy still assumed the default 19-cell prefix. With datetime and exit columns enabled, the selected command can be truncated even though the preview calculation thinks it fits.

Fixes #3599.

Validation

• cargo test -p atuin --no-default-features --features client calc_preview_height -- --nocapture - passed (2 tests)
• cargo test -p atuin --no-default-features --features client --bin atuin - passed (200 tests)
• cargo clippy -p atuin --no-default-features --features client --bin atuin -- -D warnings -A unused-variables - passed
• cargo fmt --all -- --check - passed

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[github-actions]

Fossier: Manual Review Requested

@ychampion is a new contributor. A maintainer should review this PR before merging.

Score Breakdown

Total Score: 60.4/100 | Confidence: 100% | Outcome: REVIEW

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contribution_history	67	0.34	0.05
follower_ratio	1.2	0.60	0.05
bot_signals	False	0.50	0.04
open_prs_elsewhere	49	0.00	0.09
closed_prs_elsewhere	5	0.50	0.10
merged_prs_elsewhere	21	1.00	0.08
prior_interaction	0	0.00	0.08
activity_velocity	1	1.00	0.08
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contributor_stars	74	1.00	0.04

[greptile-apps]

Greptile Summary

Fixes incorrect preview-height calculation when users configure extra UI columns (datetime, exit, etc.). The old code subtracted a hardcoded 19-cell prefix (duration + time + indicator) when deciding whether the selected command is truncated; extra columns were invisible to this calculation, so the preview was never shown for commands that were actually cut off.

• command_column_width now sums the widths of all non-expanding columns plus the indicator, and subtracts that from the available width, matching the actual column layout.
• The existing regression test uses the default columns and still passes; a new test covers the reported five-column layout at width 60.

Confidence Score: 5/5

Safe to merge — the change is isolated to preview height calculation and has no effect on data or history storage.

The fix replaces a hardcoded constant with a dynamic computation that correctly accounts for all configured columns. The math reproduces the original behaviour with default columns, the new test covers the reported scenario, and there are no side effects outside the display path.

No files require special attention.

Important Files Changed

Filename	Overview
crates/atuin/src/command/client/search/interactive.rs	Adds command_column_width helper that computes the visible command column width from configured UiColumn settings instead of the hardcoded 19-cell constant; updates calc_preview_height to use it and adds a regression test for the custom-column layout.

_{Reviews (1): Last reviewed commit: "Ensure auto previews follow configured r..." | Re-trigger Greptile}