feat(web,hub): rich hover tooltips on session-list attention indicators (#941)

* feat(web): rich hover tooltips on session-list attention indicators

The session-row attention dots and the future-scheduled clock icon used
plain `title=""` attributes which gave only a one-word label ("Permission
required"). Replace those with hover/focus-revealed tooltips that name
*which* tools are blocking, count background tasks, surface the
"updated Nm ago" timestamp, and explain the pending schedule.

To make per-tool copy possible without an extra round trip,
`SessionSummary` now carries a structured slice of the pending tool
requests, capped at `PENDING_REQUEST_SUMMARY_CAP = 5` oldest-first:

  pendingRequests: Array<{ id; kind; tool; since }>

`pendingRequestsCount` remains the authoritative total;
`pendingRequestKinds` is still derived from the FULL request set so a
single `'input'` request beyond the cap still surfaces its kind on the
session row.

The tooltip primitive (`HoverTooltip`) is a CSS-driven reveal — no
portal, no positioning JS — so it composes cheaply inside the existing
session-row `<button>` and stays out of the way on touch devices, which
keep getting the same `aria-label` the old `title=""` attribute provided
to screen readers.

Test coverage: shared derivation + cap + tie-break + full-set kind
behaviour; web tooltip render across all four attention kinds plus
mixed-kind overflow suppression and aria-label exposure.

Co-authored-by: Cursor <cursoragent@cursor.com>

* feat(web): opaque tooltip surface; drop redundant 'updated Nm ago' body

Two operator-feedback fixes on the new session-list HoverTooltip:

1. Tooltip background was bg-[var(--app-bg)] - the same variable as the
   session row underneath - so the tooltip looked translucent and the row
   text bled through. Switch to bg-[var(--app-secondary-bg)] (#2C2C2E
   dark / #f3f4f6 light, both opaque) and bump shadow-md -> shadow-lg.
   Telegram-themed clients still pick up tg-theme-secondary-bg-color so
   the tooltip stays on-theme.

2. The 'unread' attention dot tooltip rendered 'New activity / Updated 5m
   ago', but the relative-time pill ('5m ago') is already on the right
   edge of the same session row. The tooltip body just duplicated info.
   Render only the title for the unread case; drop the
   session.tooltip.unread.body i18n key from en + zh-CN.

The other tooltip kinds (permission/input list tools, background lists
task count) keep their bodies - those facts are not visible elsewhere on
the row.

Co-authored-by: Cursor <cursoragent@cursor.com>

* feat(web,hub): show scheduled fire time in session-list clock tooltip

The schedule clock tooltip previously said only "Will fire when due."
while the row already showed a relative updated-at pill. Extend the
session-list API with nextScheduledAt (MIN future scheduled_at per
session, same filter as futureScheduledMessageCount) and render:

- single scheduled: "Fires in 5m · Jun 16, 1:45 PM"
- multiple: "Next in 5m · Jun 16, 1:45 PM · +2 more"

Extract formatScheduledTime from QueuedMessagesBar into web/lib/
scheduledTime.ts alongside formatFutureRelativeTime and the tooltip
composer. SSE upsert preserves nextScheduledAt until the list refetch
that already runs on schedule-related events.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(web): wire session-row keyboard focus to HoverTooltip a11y

Address PR #941 Major review: aria-describedby and tooltip visibility
were on a non-focusable inner span, so keyboard users tabbing the session
row button never received the rich tooltip description and
group-focus-within never matched.

- Session row button owns aria-describedby (attention + schedule ids)
- Add group/session-row + SESSION_ROW_TOOLTIP_FOCUS_CLASS reveal on
  :focus-visible
- HoverTooltip takes required id; drop inner aria-label/describedby
- useSessionRowTooltipIds helper composes stable row tooltip ids
- Tests for id wiring and parent-focus reveal classes

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/lib/locales/en.ts

@@ -110,10 +110,23 @@ export default {
   'session.item.newActivity': 'New activity',
   'session.item.scheduledMessage': 'Scheduled message pending',
   'session.item.scheduledMessages': '{count} scheduled messages pending',
+  'session.tooltip.permission.body': 'Approve:',
+  'session.tooltip.input.body': 'Reply to:',
+  'session.tooltip.background.count.one': '1 task running',
+  'session.tooltip.background.count.other': '{count} tasks running',
+  'session.tooltip.scheduled.body': 'Will fire when due.',
+  'session.tooltip.scheduled.fires': 'Fires {when}',
+  'session.tooltip.scheduled.next': 'Next {when} · +{more} more',
+  'session.tooltip.moreCount': '+{count} more',
   'session.time.justNow': 'just now',
   'session.time.minutesAgo': '{n}m ago',
   'session.time.hoursAgo': '{n}h ago',
   'session.time.daysAgo': '{n}d ago',
+  'session.time.inLessThanMinute': 'in <1m',
+  'session.time.inMinutes': 'in {n}m',
+  'session.time.inHours': 'in {n}h',
+  'session.time.inDays': 'in {n}d',
+  'session.time.soon': 'soon',
   'session.time.importedFromCodex.justNow': 'just imported from Codex',
   'session.time.importedFromCodex.minutesAgo': 'imported from Codex {n}m ago',
   'session.time.importedFromCodex.hoursAgo': 'imported from Codex {n}h ago',