style(web): polish the session sidebar (#1519)

* feat(web): use sidebar fold/unfold icons for sidebar toggle

* feat(web): move settings entry to a sidebar footer row

* feat(web): fully collapse sidebar with animated width transition

* feat(web): redesign sidebar colors, spacing and macos desktop chrome

* feat(desktop): center traffic lights on the 48px header row

* fix(web): restore webkit thin scrollbars and unify sidebar icon sizes

* feat(web): add Kbd keycap component and justify sidebar search shortcut

* style(web): rework sidebar palette and pin a resident sidebar toggle

* fix(desktop): sync window appearance with web UI theme so dimmed traffic lights stay visible

* feat(web): adopt Kimi design icons in the sidebar via a local icon collection

* style(web): mute workspace group title color in the sidebar

* style(web): refine sidebar typography, unify shortcut keycaps, float workspace row actions

* style(web): cap sidebar draggable width at 480px

* style(web): derive sidebar row height from type and padding, float the kebab

* chore: add changeset for sidebar UI polish

* fix(nix): update pnpmDeps hash

* style(web): put the sidebar collapse button inside the header on non-mac

* fix(nix): update pnpmDeps hash

.changeset/polish-sidebar-ui.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+web: Polish the session sidebar layout, colors, icons, and typography.