fix: render search snippets on one row and align columns by character width

[karngyan]

Claim

Two display-only defects in the human-readable output of autophagy search (crates/autophagy-cli) are fixed, so every result renders as exactly one aligned row:

1. Multiline snippets broke the single-row table layout. Codex-adapter events carry tool input with real embedded newlines/tabs. When an FTS snippet window fell outside the extracted command/cmd field, clean_snippet left those control characters in place, spilling one result across several physical lines. It now collapses every run of whitespace (newlines, tabs, spaces) into a single space via a shared collapse_whitespace helper, applied on both the command-extraction path and the JSON-stripping fallback, before the result is written.

2. Column widths were computed from byte length. Rust's formatter pads &str by character count ({:<w$} counts chars), so a byte-length budget over-counts multibyte cells and pads the column wider than its displayed content. Width is now measured with chars().count() to match the formatter's own measure.

Both are strictly cosmetic. JSON output is untouched — raw snippets and full ranking detail remain available under --output json.

Evidence

Verified against a 69k-event real-data DB copy (adapters: claude-code, codex, pi), config isolated with AUTOPHAGY_CONFIG_DIR, real DB never modified.

Defect 1 — search "output" --project <autophagy> returned 48 physical lines for 20 results before, and exactly 20 after. One result, before (spilled across 3 lines):

evt_codex_0b430bcf…    2d ago  autophagy  text  50.0%  … Error(r.[output]);
const body=r.[output].endsWith(\n)?r.[output]:r.[output]+\n;
const patch …

Same result, after (one row):

evt_codex_0b430bcf…  2d ago  autophagy  text  50.0%  … Error(r.[output]); const body=r.[output].endsWith(\n)?r.[output]:r.[output]+\n; const patch …

Line counts, before vs after, same queries: output 48→20, text 28→20, tools 24→20.

Defect 2 — covered by a deterministic unit test (column_width_counts_characters_not_bytes): a byte-length budget injects spurious trailing spaces on a multibyte cell (café—münchen); a character-count budget equal to the cell's own width adds none.

New/updated unit tests (no DB needed): clean_snippet_collapses_multiline_content_to_one_row, clean_snippet_collapses_newlines_inside_command_value, collapse_whitespace_trims_and_squeezes_runs, column_width_counts_characters_not_bytes.

mise run check (fmt + clippy pedantic -D warnings + tests + docs + actionlint) passes fully (exit 0).

Privacy

None. Display-only changes to human-readable output; no new persistence, no change to what is indexed or stored, JSON output byte-for-byte unchanged.

Scope

Single file: crates/autophagy-cli/src/main.rs. No spec, schema, or migration changes.

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