feat(web): add collapsible session sidebar

[wu736139669]

Summary

• add desktop controls to collapse and expand the session sidebar
• keep a 96px compact session rail with project grouping and live status indicators
• persist the collapsed preference locally while keeping the sessions index and mobile layout expanded
• hide secondary row metadata and inaccessible schedule tooltip references in compact mode

Testing

• bun typecheck
• bun run test

[github-actions]

Findings

• [Major] Compact mode bypasses the session preview cap and mounts the full session history (web/src/components/SessionList.tsx:1604).
• [Minor] Search/date/unread filters remain active after their controls are hidden (web/src/components/SessionList.tsx:1792).

Summary
Review mode: initial

Two issues found in the compact session-list path. No questions required.

Testing
Not run (automation): executing PR code is disallowed for this review. GitHub integration check passed; the main test workflow was pending at review time. Missing coverage: compact preview limits/expansion and collapsing while transient filters are active.

HAPI Bot

[github-actions]

[MAJOR] Compact mode bypasses the preview cap

compact ? group.sessions : ... mounts every session in every directory instead of using the configured preview limit. Collapsed panels still retain their children, and /api/sessions has no default result limit, so a long-lived installation can turn one sidebar-collapse click into hundreds or thousands of SessionItem trees/hooks and stall the page.

Suggested fix: keep the existing preview helper in compact mode and expose an icon-only expansion affordance for hidden rows.

const visibleGroupSessions = getVisibleGroupSessions(group)

{compact && hiddenSessionCount > 0 ? (
    <button
        type="button"
        onClick={() => showMoreSessions(group)}
        aria-label={t("sessions.group.expand", { n: expandCount })}
    >
        <SessionPreviewArrowIcon direction="down" className="h-3 w-3" />
    </button>
) : null}

[github-actions]

[MINOR] Hidden filters keep filtering the compact rail

Changing showSearch to false only unmounts the controls. searchQuery, the custom date range, and showUnreadOnly still feed visibleSessions, so collapsing after a search/date/unread selection can produce a silently incomplete or empty rail with no visible way to understand or clear the filter until the user expands again.

Suggested fix: ignore transient filters while compact, preserving their state for when the sidebar is expanded again.

const isFiltering = !compact && (normalizedQuery.length > 0 || timeRange !== null)

const unreadFilteredSessions = useMemo(() => {
    if (compact || !showUnreadOnly) return visibleSessions
    // existing unread filtering
}, [compact, lastSeenVersion, visibleSessions, selectedSessionId, showUnreadOnly])