feat(web): draw the sidebar's scrollbar only under the pointer

The session list overflows after a handful of sessions, and its scrollbar was drawn permanently in a column that is at rest most of the time. SidebarRoot now tracks the pointer over the whole column and rebinds ui-theme's scrollbar indirection pair to `transparent` while it is outside, keeping the thumb for 2s after the pointer leaves so it does not blink out on the way past. Rebinding colour leaves the list's `scrollbar-gutter: stable` reservation in force, so revealing the bar moves no row. ui-theme's gate now states the widened contract: a rebind targets an -l2 token pair or `transparent`, and nothing else.
2026-08-04 15:05:32 +08:00
parent 3c436d781e
commit a030397aca
20 changed files with 430 additions and 28 deletions
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/client/ui-sidebar/README.md
-README.md: 19c2d1033de4475816249aa8429f4a589eeb6481
-README.zh.md: b8c154586570cf1b9fd4bf776bc09b36ab5ee7d2
+README.md: 5bb697b3d2f9b5eaea9c382765d2510fa24806ce
+README.zh.md: 302f66c540774b1f209fc797201e41c56b849310