fix(mobile): css batch 2 — the phone layout fixes from the 3.5.3 screenshots

[Nezreka]

fixes the phone css batch thibs, c5pie and gzetk reported (22 screenshots, all on 3.5.3). every item was measured in chromium at 390/360/320 before and after, not eyeballed.

six root causes:

• a global mobile rule forced every button to min-height 38px, stretching anything designed shorter — theme swatches rendered as 16x38 ovals, library and import pills protruded from their tracks. the victims are excluded from the rule now (import pills via a data attribute, their class is a hashed css module); standalone buttons keep the 38px target.
• the tab-rail fix in fix(mobile): compact drawer header in landscape so nav can scroll #1661 only reached rails with its exact class names. the react watchlist tabs never matched (tabs measured 391px in a 336px box, chips ran off to x=1089) — they carry role="tablist" now so the rail rule applies. the library settings folders switcher was squeezed by a more specific rule, "audiobooks" painted over "podcasts" — it scrolls instead of squeezing.
• fixed min-widths that never collapsed on phones: tools triage/pillars grids (280px/320px floors), the pillars header paragraph had no css at all and collided with the title, downloads chain, logs toolbar (the green sliver was the auto-scroll toggle pushed off screen), quality presets, video issues stats, audiobooks search (420px flex basis).
• hamburger coverage from fix(mobile): compact drawer header in landscape so nav can scroll #1661 only knew the legacy classes. settings sub-titles use a different class and still slid under it ("…brary", "…wnloads"), and the modal-hide rule waited for classes nothing sets — it now keys off the classes the app actually toggles (src/pf/np-modal-open) plus :has() on the react overlay roots, and the audiobook overlay stamps a data attribute since its backdrop class is hashed.
• player: the play button is 70px in a flex row with no flex-shrink: 0, so it compressed into an oval — transport buttons don't shrink now and the row is budgeted for phones. the tab panels sat in a second 46vh scroller, which is why the bottom (and the eq) felt unreachable; panels flow in the body scroll on mobile. the minimize chevron was parked half off-screen by a stacking rule, and once visible it still wasn't tappable (a sibling layer with the same z-index covered it) — z-index raised and verified with a real click.
• dashboard listen band (library radio / your mixes) was a two-column grid that never stacks — content measured 344px in a 174px card, clipped mid-word. it stacks at phone widths now. the earlier "that's the make horizontal scrollbars visible with edge-fade slide affordance #1637 rail working as designed" call was wrong; these cards aren't the rail.

folded in from two hostile review rounds: the phone transport sizing initially crushed the player's stop button (a text pill, not a transport circle) — scoped to the controls row; three more modal families added to the hamburger coverage (watchlist-add, server-disambiguation, genre browser); 320px residuals fixed (tools mode toggle, audiobooks search modes, downloads step name).

tests: 30 new css/tsx pinning tests (28 fail on the base), npm run check clean, full vitest suite green (10,268). phone screenshot baselines in ci will diff on the touched pages — the layouts changed on purpose; desktop is untouched (everything is inside phone media queries, the exclusion list, or phone-only rules).

note: the reporters are on 3.5.3, so the #1661 fixes they also don't have yet (ios input zoom, import rail scroll, video wishlist rail) will keep looking broken to them until a release ships both.