feat(ui): the track list a phone can read

B2 phase 4, and the last of it. Measured on the device: at 424 CSS px
the four configured columns fit the row *exactly* -- `--grid-cols` came
out `24px 102px 101px 101px 80px` -- and not one of them fit its
content, with "Duration" too narrow for its own header. The columns were
never too wide; there were too many of them.

So a phone draws `titleArtist` (the title with the artist under it,
across the row's whole width) plus the duration, and drops the column
headers and the resize handles, which are a click-to-sort and a drag
with no touch equivalent. It is a **column set, not a second row
template**: the row, its delegated events, the selection semantics, the
playing marker and the virtualizer never learn anything changed, because
from their side only the number of columns did.

Three rules come with it. The row height is in two places
(`PHONE_ROW_HEIGHT` and the CSS rule) and must agree, since the
virtualizer positions rows from that number and a taller row overlaps
its neighbour. What is drawn and what can be sorted are different
questions, so the sort list is built from `configuredColumns` -- a phone
has no headers either, and building it from the drawn columns would
leave it able to sort by title and duration alone. And a phone's column
widths are neither loaded nor saved.

That third rule is the bug the device found with the arrangement already
passing five component tests and five e2e specs at the phone's own
viewport. `loadColumnWidths` is keyed by column *id* and fills a gap
with `MIN_COLUMN_WIDTH`, so the stacked column -- which nothing can ever
have saved a width for -- came out at 148px beside a duration column of
236. The mirror image was worse and unreachable from a phone at all:
saving would have written those widths back under the same ids,
replacing the width the user dragged on a desktop. The specs asserted
shape, and the fault depended on what `localStorage` held for a
different column set; the unit test now carries that map as a fixture.

Verified: 809 component tests, 112 e2e specs, and on the phone at
424x439 -- `24px 304px 80px`, 52px rows, no truncation, no overflow.
One full e2e run of three saw an unrelated autotag keypress spec flake
and pass on retry.

.planning/NOTES.md

@@ -3257,3 +3257,47 @@ done (`adb uninstall app.yellowjacket.dev` — the sibling id is exactly
 what makes that safe). And `am start` does not reliably take focus while
 another app is foreground: check `topResumedActivity` before trusting a
 screenshot, or you will read someone else's app.
+
+## The phone track list, and the bug a viewport could not have found (2026-08-17)
+
+B2 phase 4. A phone draws `titleArtist` — the title with the artist
+under it — plus the duration, and drops the column headers and the
+resize handles. It is a **column set, not a second row template**: the
+row, its delegated events, the selection semantics, the playing marker
+and the virtualizer never learn that anything changed, because from
+their side only the number of columns did.
+
+Three rules, each one a way it breaks otherwise. The row height is in
+two places (`PHONE_ROW_HEIGHT` and the CSS) and they must agree, since
+the virtualizer positions rows from that number. What is *drawn* and
+what can be *sorted* are separate questions — the sort list is built
+from `configuredColumns`, or a phone with no headers could sort by
+nothing but title and duration. And a phone's widths are neither loaded
+nor saved.
+
+**That last one is the finding, and it came from the device.** With the
+arrangement passing five component tests and five e2e specs at
+424x439, the phone showed `24px 148px 236px`: the duration column with
+55% of the row. `loadColumnWidths` is keyed by column *id* and fills a
+gap with `MIN_COLUMN_WIDTH`, so the stacked column — which nothing can
+ever have saved a width for, there being no handles to drag — came out
+at the minimum while `trackLength` inherited a width saved for a
+four-column desktop row. The mirror image is worse and was never
+reachable from a phone at all: `saveColumnWidths` would have written the
+computed phone widths back under the same ids, replacing the width the
+user dragged on a desktop.
+
+**Why every browser test missed it.** The specs assert the *shape* — how
+many grid tracks, no header, no overflow, the title's share of the row —
+and the width bug depends on what is in `localStorage` for a *different*
+column set. dev-headless's seed happened to hold widths that split the
+other way, so the same assertion passed in the browser and failed on the
+phone. The unit test now carries the desktop map as a fixture, which is
+the reproduction the browser needed to have.
+
+Two tooling notes worth keeping. `playwright-cli` holds its page across
+a `make dev-headless` restart, so a probe after a rebuild can be
+answering for the *old* bundle — it reported the desktop layout at 424 px
+until the page was reopened. And wireless adb dropped twice more mid-
+session when the screen slept; USB for anything longer than a few
+probes.