feat(app): sidebar display preferences, a shared menu engine, and a colour pass

Sidebar polish round.

Menus. `dropdown-menu` and `context-menu` were two copies of one engine that
differed only in how the trigger fires — identical from `computePosition` down —
and neither could nest. Both are now thin wrappers over
`components/ui/menu/`, which owns anchoring, a pure page-stack navigation model,
and one presentation fork: flyout on pointer, pushed pages in a sheet on compact.
All 31 call sites are unchanged. Items got a rounded inset fill, a visible
separator, and `selected` (a check) split from `active` (a fill).

Sidebar display preferences. The flat wall of four sections becomes one row per
decision with its value, and per-feature toggles over what a workspace row shows:
host, pull request, checks, scripts. Each is independent — a ticked toggle that
draws nothing is a lie. `display-preferences/` hides that grouping lives in
zustand while title source and row items are app settings.

Timestamps. "Last activity" now ticks itself. The label rounds to the minute and
never shows seconds; past a week it becomes a date. The timer lives in the leaf
`<Text>`, at most one per resolution tier shared by every row, and a tick only
re-renders when the string actually changed — so a memoized row that legitimately
never re-renders still stays current.

Colour. Full status tier regenerated at 90% of gamut max (was 85), same rule as
the muted tier, lightness and hue untouched. File icons are pulled toward neutral
in OKLab behind `getFileIconSvg` — material-icon-theme picks its palette for a
tree where the icon is the only colour on the row, and ours is not. New/deleted
files use the forge square-plus/square-minus glyphs at muted weight instead of
tinted pills. Project icons round a little more; uploaded icons never do.

The project status badge is a knockout again: it fills with the colour of the row
behind it, so the ring reads as a gap in the icon rather than a white halo.

File rows. The always-visible kebab is gone from the file explorer and diff tree
in favour of right-click, which also reclaims the reserved action slot.

packages/app/src/styles/theme.ts

@@ -109,42 +109,64 @@ export const baseColors = {
 
 export type ThemeName = "light" | "dark" | "zinc" | "midnight" | "claude" | "ghostty";
 
-// Diff colors — light uses muted tones, dark uses the brighter palette values.
+// Diff colors — the +/- inside a diff view, where the color *is* the signal and has to
+// survive being scanned line by line, so it stays saturated. Light uses muted tones, dark
+// uses the brighter palette values.
 //
-// Two tiers, because the +/- serves two jobs. In the diff view the color *is* the signal and
-// has to survive being scanned line by line, so it stays saturated. In a row's metadata the
-// counts are a footnote next to a title and a subtitle; at full saturation they read as the
-// loudest thing in the row. The Stat tier keeps the hue but drops the chroma to roughly the
-// weight of foregroundMuted, so it sits with the subtitle instead of shouting over it.
+// A diff *stat* — the "+12 −3" footnote next to a title — is not this. It reads as one of
+// several muted signals in a row, so it uses statusMutedSuccess/Danger below rather than a
+// near-duplicate tier of its own.
 const lightDiffColors = {
   diffAddition: "#15803d", // green-700 — readable on white without screaming
   diffDeletion: "#b91c1c", // red-700
-  diffStatAddition: "#32794a", // softened green-700
-  diffStatDeletion: "#a43c39", // softened red-700
 };
 
 const darkDiffColors = {
   diffAddition: "#4ade80", // green-400
   diffDeletion: "#ef4444", // red-500
-  diffStatAddition: "#61bf82",
-  diffStatDeletion: "#d36461",
 };
 
-// Status colors — semantic signals for success/danger/warning/merged. Used by
-// check statuses, PR states, and review decisions. Kept a step darker than the
-// raw palette so they read as signals, not neon.
+// Status colors — semantic signals for success/danger/warning/merged. Used by check
+// statuses, PR states, and review decisions.
+//
+// Normalized, not hand-picked. Every color below shares one lightness and one chroma within
+// its tier; only the hue changes, and each hue is the one that family already had. Chroma is
+// a fixed fraction of what sRGB allows at that lightness and hue, because the gamut is
+// lopsided — amber runs out of room long before red does, so a literal equal-chroma set
+// leaves amber flat and red screaming. Equal fractions is what makes four hues read as one
+// family. Regenerate with the same rule rather than nudging one value.
+//
+// Two tiers. Full is for a surface whose job is to report the status — the PR pane, a usage
+// bar. Muted is for the same signal repeated on every row of a dense list, where full
+// saturation makes the list itself the loudest thing on screen; it sits at roughly
+// foregroundMuted's weight so a row built from it reads as one line of subtitle.
+//
+// Deliberately not on this scale: the workspace status dot. That one is supposed to shout,
+// so it keeps the raw palette — see getStatusDotColor.
 const lightStatusColors = {
-  statusSuccess: "#15803d", // green-700
-  statusDanger: "#b91c1c", // red-700
-  statusWarning: "#d97706", // amber-600
-  statusMerged: "#7c3aed", // purple-600
+  // L=0.53, chroma 90% of gamut max
+  statusSuccess: "#1f8040",
+  statusDanger: "#c32424",
+  statusWarning: "#91601b",
+  statusMerged: "#8728e5",
+  // L=0.50, chroma 45% of gamut max
+  statusMutedSuccess: "#496d50",
+  statusMutedDanger: "#904d46",
+  statusMutedWarning: "#755f45",
+  statusMutedMerged: "#6e519d",
 };
 
 const darkStatusColors = {
-  statusSuccess: "#16a34a", // green-600
-  statusDanger: "#dc2626", // red-600
-  statusWarning: "#f59e0b", // amber-500
-  statusMerged: "#9333ea", // purple-600
+  // L=0.66, chroma 90% of gamut max
+  statusSuccess: "#2ead58",
+  statusDanger: "#f65048",
+  statusWarning: "#c38328",
+  statusMerged: "#a670f5",
+  // L=0.70, chroma 40% of gamut max
+  statusMutedSuccess: "#7cac85",
+  statusMutedDanger: "#ca8c85",
+  statusMutedWarning: "#b79875",
+  statusMutedMerged: "#a594c6",
 };
 
 // Semantic color tokens - Layer-based system