chore: audit all components (#2)

Reviewed-on: #2

docs/CHECKLIST.md

@@ -11,6 +11,9 @@ is the first downstream consumer; its screens drive the order.
 
 ## Queue — to follow
 
+Platform metric adoption continues one component at a time; each stop goes
+through the review gate and a gallery pass.
+
 Gaps surfaced by the signed comparison; ordered by signed's usage.
 
 - [ ] **Virtual list** — generic virtualized variable-height rows with a
@@ -47,6 +50,14 @@ Gaps surfaced by the signed comparison; ordered by signed's usage.
 - [x] Platform sources — macOS (NSColor), Windows 11 (UISettings), GNOME
       (portal), KDE (kdeglobals), Omarchy (colors.toml), neutral fallback;
       live watchers for each
+- [x] Platform metric fidelity — stated control/input/menu-row/switch
+      metrics and the full radius ladder per platform, Linux root fonts
+      (GNOME gsettings `font-name`, KDE `kdeglobals font=`), per-source
+      border + focus chrome (`Theme::borders`), and a per-platform spacing
+      unit (`Theme::spacing`); overlay borders engage in dark mode, where
+      floating layers separate by border instead of shadow — dark elevation
+      shadows are dropped entirely, since they only muddied the dark scrim.
+      Components adopt the tokens one by one (see Next and Queue)
 
 ### icons (`crates/icons`)
 
@@ -55,12 +66,93 @@ Gaps surfaced by the signed comparison; ordered by signed's usage.
 
 ### core (`crates/core`)
 
+- [x] Button platform chrome — every variant always paints the hairline
+      border, sized outside the stated control height (`BORDER_WIDTH`); where
+      the platform paints no border (`Theme::borders.buttons`, ghost) the
+      border takes the fill's color and disappears, so sizes match across
+      platforms; icon-bearing buttons pad with `dense_padding_x` instead of
+      `padding_x`
+- [x] Button loading state — `.loading(true)` shows the spinner in place of
+      the icon and suppresses activation; Spinner gained a `.color` override
+      for accent-filled surfaces
+- [x] Input platform chrome — the field always paints the hairline border,
+      sized outside the stated field height; where the platform paints no
+      border (`Theme::borders.fields`) it takes the field's fill; focus
+      recolors the border on Windows / KDE and paints the accent ring on
+      macOS / GNOME via `Theme::borders.focus_ring`; the shared `focus_ring`
+      band paints at half ink (every focusable control picks it up)
+- [x] Input prefix / suffix — elements docked inside the field's edges,
+      typically small ghost buttons; a docked click activates the control
+      without reaching the field's caret handler, and the text region shrinks
+      to make room
+- [x] Select platform chrome — the trigger takes the input treatment: the
+      hairline border always painted, sized outside the stated field height
+      and taking the fill's color where the platform paints none; open
+      recolors the border on Windows / KDE and paints the accent ring on
+      macOS / GNOME, so the trigger matches a focused field; the menu
+      popup's border sits behind `Theme::borders.overlays`, disappearing
+      into the surface where the platform paints none
+- [x] Menu platform chrome — the popup border behind `Theme::borders.overlays`
+      (and dark mode); the panel padding and separator margins come from
+      `Theme::spacing`, and every action row renders at the stated
+      `menu_item_height` with content centered, so the stated metric is the
+      whole row; rows carry debug selectors for headless geometry tests
+- [x] Popover platform chrome — the panel border behind
+      `Theme::borders.overlays` (and dark mode); the anchor gap is the
+      spacing unit and rides `anchored().offset`, not a margin, so the
+      window-edge clamp stays intact; the panel carries a debug selector
+- [x] Dialog platform chrome — the panel border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none
+- [x] Toast platform chrome — the pill border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none; the pill rides the popover elevation,
+      so dark mode's no-shadow rule applies to it too
+- [x] Tooltip platform chrome — the panel border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none, and riding the popover elevation for
+      the light-mode shadow; anchored tooltips hang below the
+      hovered parent (`Tooltip::anchored(text, id)`) so they never cover it —
+      the element records its painted bounds with `record_anchor_bounds`
+      (`Button` does), the panel hangs below that with the spacing gap, and
+      it flips above the parent when it would overflow the window bottom
+      (the panel records its own height after the first frame); unanchored
+      tooltips fall back to the cursor-offset wrapper
+- [x] Alert platform chrome — the banner border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none; it rides the popover elevation, so
+      dark mode's no-shadow rule applies to it too
+- [x] Combobox platform chrome — the popup border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none, and riding the popover elevation for
+      the light-mode shadow; the trigger is a plain `Input`, so it
+      already carries the full field treatment, and the chevron recenters on
+      the field's full height, border included; the popup mounts on
+      `deferred(anchored().offset(...))` like the Popover — out of the
+      wrapper's layout, one spacing gap below, window-clamped — and always
+      matches the combobox's width; the combobox itself is no longer full
+      width: it takes a compact default and style refinements on the builder
+      (`.w(...)`) set the width; the empty field keeps its placeholder while
+      focused (`Input::placeholder_when_focused`) and clicking into it opens
+      the options right away, with no keystroke needed
+- [x] Command palette platform chrome — the panel border behind
+      `Theme::borders.overlays` (and dark mode), taking the surface color
+      where the platform paints none; it rides the dialog elevation, so dark
+      mode's no-shadow rule applies to it too
+- [x] Switch platform chrome — the track and knob take the stated
+      `switch_height` / `switch_width` / `switch_knob` (the knob's inset
+      derived to center it in the track, its travel from the remaining
+      width); the knob is borderless, and the track carries a debug selector
+      for headless geometry tests
 - [x] Button, Checkbox, Switch, Radio + RadioGroup, Toggle, Link, Slider,
       Progress, Avatar (image + seeded pixel-art fallback)
 - [x] Spinner — painted ring + rotating-icon variant, indeterminate and
       determinate; replaces `Tab::busy`'s placeholder
 - [x] Input — single-line, password with reveal, multiline, undo/redo, actions
-      + key context, caret blink
+      + key context, caret blink (time-math driven: the focused field mounts a
+      repeating blink animation whose frames redraw the caret, the caret is
+      solid for one interval after each edit, and an idle unfocused page
+      schedules no frames)
 - [x] ScrollArea, Popover, Menu, Tooltip, Dialog / AlertDialog, Toast,
       Alert + alerts stack
 - [x] Select, Segmented, ContextMenu, EmptyState, Badge
@@ -70,7 +162,8 @@ Gaps surfaced by the signed comparison; ordered by signed's usage.
       screen-reader label
 - [x] Combobox — type-to-filter picker with a caller-owned matcher, create /
       keep / revert blur modes
-- [x] Command palette — filtered actions; the matcher stays caller-owned
+- [x] Command palette — filtered actions; the matcher stays caller-owned,
+      and commands may carry a leading icon
 - [x] Scrollbar — overlay thumbs for gpui's `list` and `uniform_list`,
       platform autohide with a `visibility` override
 - [x] Clipboard button — copies a value, confirms with a brief check mark