fix(cli): stop compact list projection from mangling short fields

[ysyneu]

Problem

The default compact projection used by `alert-event list`, `incident list`, and `incident similar` (in json/toon mode, when `--fields` is omitted) computed a single per-field byte cap by dividing the total budget by the total count of string values across every row, then geometrically halved that cap whenever the aggregate output still overflowed 16 KiB.

Each halving re-applied the shrinking cap to every string field on every row, including fields that were never responsible for the overflow (e.g. Mongo ObjectID-shaped ids, or short enum-like severity/status strings), clipping them down toward a 1-byte cap even though a single long field (typically the title) was the actual cause.

Once the cap dropped to 3 bytes or below, the truncation helper had no room left for its "..." marker and fell back to returning raw, unmarked bytes — making a shortened value indistinguishable from a genuinely short one. Piping such output to jq/grep for an exact id or status match then silently returns no hits, with no indication the field was ever truncated.

Fix

Replace the per-field cap computation with a search for the largest single cap that lets the whole page fit, then apply it once:

• A field already shorter than that cap is left completely untouched, so only the field(s) actually responsible for the overflow get shortened.
• The cap is never allowed to drop low enough to lose the "..." marker.
• When no such cap exists, the command now fails with an actionable error instead of emitting values that look real but aren't.

alert-event list, incident list, and incident similar all share this helper (boundProjectedList in internal/cli/fieldproject.go), so the fix applies to all three. alert list is unaffected — it doesn't run through this default compact-projection path.

Tests

• A fixture with long ids and a minority of oversized multi-word/CJK titles confirms the ids and short titles stay intact in both json and toon output, while only the oversized titles are marked-truncated.
• A --fields path test confirms explicit field selection is unaffected.
• A low-level test forces every string field to shrink under extreme pressure and asserts the "..." marker is never dropped.

`go vet ./...`, `gofmt -s -l`, `make lint` (0 issues), and `go test ./...` all pass.