refactor(design): Linear-aligned dual-theme tokens + inset-card shell

design tokens
- color.ts rewritten via lch(): hue 282 (light) / 272 (dark), paired L
  sums ~100 (mirror constraint). Status colors split fg/bg per theme and
  opted out of the mirror (semantics > aesthetics). Brand lavender
  theme-invariant; only hover/focus pivots between themes.
- sidebar chrome tokens introduced (bgSidebar / bgSidebarRow /
  bgSidebarChip / sidebarTreeLine). bgSidebar = canvas — sidebar and
  AppShell outer wrapper share the chrome plane so the focal main card
  is the only contrasting surface.
- hairline ladder rebalanced (>=2.5 L away from surface1 in both
  themes); original Linear-measured L=6.77 collided with our surface1.
- chrome tokens for sidebar geometry (width 244, row 28, header 52,
  section gap 24, inset 12, indent 16).
- typography: navItem (13/500) + navGroup (12/500) presets.
- inverse* tokens for forced-polarity surfaces.

theme switching
- theme.css.ts: two createGlobalTheme blocks. :root, :root.dark default
  + :root.light override via specificity (0,2,0 > 0,1,0).
- stores/ui.ts: toggle BOTH .dark and .light document classes (was
  dark-only — light never actually applied).

shell layout
- AppShell mainStyle becomes an inset card: surface1 + radius.md +
  8px margin (6px left for sidebar gap) + hairline border + overflow
  hidden. Visible 3-plane ladder: sidebar (chrome) ↔ canvas gap ↔ main
  card (focal).
- Sidebar redesigned to Linear rhythm: workspace header 52 px, rows
  28 px, group gap 24 px, hierarchy by (lightness × indent × static
  500 weight), no right border, counter pill with active-row text
  highlight, nested L4 subtree with connector line.
- FullLayout / TwoColLayout repainted to surface1 so all panes share
  the focal plane inside the inset card; pane divider lifted from
  hairlineTertiary to hairline (whisper hairline vanishes against
  surface1).
- ColumnHeader rootRecipe bg: canvas → surface1 (used by ListSubHeader
  + PostHeader; keeps the focal plane unified).
- RightPane paneStyle bg: canvas → surface1 (same intent).

DESIGN.md
- §0 dual-theme philosophy added.
- §1 rewritten as dual-theme palette: mechanics, surface ladder,
  sidebar chrome, hairlines, ink, brand (theme-invariant), status
  fg/bg, inverse, status dots.
- §1.9 notification & list color encoding (Linear inbox audit):
  status colour rides only on ≤14 px glyphs, read/unread by ink
  strength only, max two colour cues per row, embed cards keep
  surface1 body + 2-3 px coloured left-border.
- §7.5 sidebar three-axis hierarchy doc.
- §7.6 main-as-inset-card shell with ASCII diagram.
- §10 anti-patterns extended.
- §12 calibration history v3-v6.

Author: Innei

DESIGN.md

@@ -31,7 +31,7 @@ export const KebabMenu = ({
   onDelete,
 }: KebabMenuProps) => {
   const [open, setOpen] = useState(false)
-  const triggerSize = variant === 'compact' ? 'sm' : 'md'
+  const triggerSize = 'sm'
 
   const close = (fn?: () => void) => () => {
     setOpen(false)

src/components/post-detail/header/KebabMenu.tsx

@@ -7,7 +7,7 @@ export const externalLinkFullStyle = style({
   display: 'inline-flex',
   alignItems: 'center',
   gap: 6,
-  height: 32,
+  height: 28,
   paddingInline: '10px',
   background: 'transparent',
   border: 'none',

src/components/post-detail/header/PostHeader.css.ts

@@ -41,7 +41,7 @@ export const PostHeader = ({
   onOpenDiff,
   externalUrl,
 }: PostHeaderProps) => {
-  const iconSize = variant === 'compact' ? 'sm' : 'md'
+  const iconSize = 'sm'
   const isFull = variant === 'full'
   const title = post?.title ?? ''
   const publishDisabled = dirtyFieldCount === 0

src/components/post-detail/header/PostHeader.tsx

@@ -38,7 +38,7 @@ export const PublishMenu = ({
     <div className={publishMenuRootStyle} data-testid="publish-menu">
       <Button
         intent="primary"
-        size={variant === 'full' ? 'md' : 'sm'}
+        size="sm"
         disabled={disabled}
         onClick={onPublish}
         className={
@@ -55,7 +55,7 @@ export const PublishMenu = ({
           render={
             <Button
               intent="primary"
-              size={variant === 'full' ? 'md' : 'sm'}
+              size="sm"
               aria-label="发布选项"
               className={
                 variant === 'full'

src/components/post-detail/header/PublishMenu.tsx

@@ -9,7 +9,7 @@ export const rootRecipe = recipe({
     display: 'flex',
     alignItems: 'center',
     height: chrome.headerHeight,
-    background: themeContract.color.canvas,
+    background: themeContract.color.surface1,
     borderBottom: `1px solid ${themeContract.color.hairline}`,
     flexShrink: 0,
   },

src/components/ui/ColumnHeader/ColumnHeader.css.ts

@@ -27,7 +27,14 @@ export const mainStyle = style({
   display: 'flex',
   flexDirection: 'column',
   minWidth: 0,
-  height: '100%',
+  // Linear-style inset card: 主面浮于 chrome canvas 之上
+  // canvas (gap) ←→ sidebar (deepest chrome) ←→ main card (brightest focal)
+  background: themeContract.color.surface1,
+  borderRadius: themeContract.radius.md,
+  marginBlock: '8px',
+  marginInlineEnd: '8px',
+  marginInlineStart: '6px',
+  border: `1px solid ${themeContract.color.hairline}`,
   overflow: 'hidden',
 })