feat(web): session list one-list, hover card, row menus, rename, manual ordering

Sidebar session list grows the figma 239-10458 feature set and the
workspace/session browsing region moves wholesale into ui-workspace:

- Group-by menu (WorkSpace / In one list): flat mode lists every session
  top-level, strictly newest-first; the choice persists across reloads.
- Session rows get a 500ms hover detail card (title / relative time /
  status line) and a ... menu (Rename / Fork session / Delete session,
  visual-only for now); workspace headers get ... with Rename (wired) and
  Delete workspace (visual-only).
- workspace.rename RPC: trims, rejects duplicate titles on the create
  chain (workspace-name-conflict), no-op on same title; modal dialog with
  client-side duplicate pre-check.
- workspace.insertSessionBefore RPC (DOM-insertBefore semantics, omitted
  anchor appends): HTML5 drag reorder of root sessions inside a workspace
  group; order truth stays host-side, the view refreshes from the
  response/changed frame.
- Activity pinning removed: the session/event touchSession chain is gone;
  workspace accounts are manually owned (new sessions prepend, explicit
  reordering only). Contracts and tests updated, api catalog regenerated.
- ui-sidebar reduced to the column shell (brand, fold state machine, New
  Session, Settings) exposing one sidebar.workspaces hole with a two-fact
  owner share {wide, expandSidebar}; ui-workspace owns the whole region
  (header, search, grouped/flat lists, dialogs, drag) plus the picker via
  a shared WorkspaceCreateFlow. The old sidebar.workspace picker slot and
  its deferral indirection are gone.
- ui-primitives: Menu gains label entries, danger rows, and
  closeOnPointerLeave; new HoverCard (portaled, open-delay, disabled
  guard). Hover card and row menu never coexist.

packages/client/ui-primitives/src/Menu.tsx

@@ -4,6 +4,7 @@
 // the anchor rect, for anchors inside overflow-clipping containers (sidebar).
 // The owner controls `open`; outside-click closing uses one document listener
 // active only while open. Submenus open on hover/focus inside the same root.
+// Entries also cover non-interactive `label` headings and `danger` rows.
 
 import { useEffect, useLayoutEffect, useRef, useState } from 'react'
 import type { CSSProperties, ReactNode } from 'react'
@@ -19,6 +20,8 @@ export interface MenuItem {
   disabled?: boolean
   /** Leading icon (figma .Menu_cell gap 8). */
   icon?: ReactNode
+  /** Destructive row: error-colored text/icon and danger hover fill. */
+  danger?: boolean
   /** Nested card opened to the right on hover/focus. */
   submenu?: readonly MenuItem[]
 }
@@ -29,13 +32,24 @@ export interface MenuSeparator {
   id: string
 }
 
-/** One primary-menu entry: a row or a separator. */
-export type MenuEntry = MenuItem | MenuSeparator
+/** Non-interactive heading row above a group of items. */
+export interface MenuLabel {
+  type: 'label'
+  id: string
+  text: string
+}
+
+/** One primary-menu entry: a row, a separator, or a heading label. */
+export type MenuEntry = MenuItem | MenuSeparator | MenuLabel
 
 function isSeparator(entry: MenuEntry): entry is MenuSeparator {
   return 'type' in entry && entry.type === 'separator'
 }
 
+function isLabel(entry: MenuEntry): entry is MenuLabel {
+  return 'type' in entry && entry.type === 'label'
+}
+
 /**
  * Render an anchored dropdown menu.
  * @param props.open - whether the list is showing (owner-controlled).
@@ -50,6 +64,8 @@ function isSeparator(entry: MenuEntry): entry is MenuSeparator {
  * from the anchor rect (repositions on scroll/resize while open). Use when an
  * ancestor's overflow clipping would crop the in-place list; default false
  * keeps the pure-CSS in-place behavior.
+ * @param props.closeOnPointerLeave - close the list when the pointer leaves
+ * it (default false keeps it open until outside click/Escape/selection).
  * @param props.getAnchorRect - portal mode only: supply the anchor rect
  * directly (e.g. from a host-owned trigger button) instead of measuring the
  * Menu's own wrapper span. Required when the wrapper isn't itself laid out at
@@ -58,7 +74,7 @@ function isSeparator(entry: MenuEntry): entry is MenuSeparator {
  * scroll/resize; return null to skip placement for that frame.
  * @returns anchor wrapper with the conditional list.
  */
-export function Menu({ open, anchor, items, selectedId, onSelect, onClose, align = 'start', side = 'bottom', portal = false, getAnchorRect, className }: {
+export function Menu({ open, anchor, items, selectedId, onSelect, onClose, align = 'start', side = 'bottom', portal = false, closeOnPointerLeave = false, getAnchorRect, className }: {
   open: boolean
   anchor: ReactNode
   items: readonly MenuEntry[]
@@ -68,6 +84,7 @@ export function Menu({ open, anchor, items, selectedId, onSelect, onClose, align
   align?: 'start' | 'end'
   side?: 'bottom' | 'top'
   portal?: boolean
+  closeOnPointerLeave?: boolean
   getAnchorRect?: () => DOMRect | null
   className?: string
 }) {
@@ -135,11 +152,19 @@ export function Menu({ open, anchor, items, selectedId, onSelect, onClose, align
       className={clsx(css.list, portal && css.portal, side === 'top' && !portal && css.sideTop, align === 'end' && !portal && css.alignEnd)}
       style={fixedPos ?? undefined}
       role="menu"
+      onPointerLeave={closeOnPointerLeave ? () => { onClose() } : undefined}
+      // React portals bubble synthetic events through the REACT tree: without
+      // this stop, an item click re-fires the anchor row's own onClick
+      // (open/toggle) after onSelect.
+      onClick={(e) => { e.stopPropagation() }}
     >
           {items.map(entry => {
             if (isSeparator(entry)) {
               return <div key={entry.id} className={css.separator} role="separator" />
             }
+            if (isLabel(entry)) {
+              return <div key={entry.id} className={css.label} role="presentation">{entry.text}</div>
+            }
             const hasSub = entry.submenu !== undefined && entry.submenu.length > 0
             const subOpen = hasSub && openSubmenuId === entry.id
             return (
@@ -152,7 +177,7 @@ export function Menu({ open, anchor, items, selectedId, onSelect, onClose, align
                 <button
                   type="button"
                   role="menuitem"
-                  className={clsx(css.item, entry.id === selectedId && css.selected)}
+                  className={clsx(css.item, entry.id === selectedId && css.selected, entry.danger === true && css.danger)}
                   disabled={entry.disabled}
                   aria-haspopup={hasSub ? 'menu' : undefined}
                   aria-expanded={hasSub ? subOpen : undefined}