feat: session quick wins (#51-#55) (#72)

* feat: add session quick wins (#51-#55)

- Session timer showing elapsed time in header (#51)
- Tab keyboard shortcut to focus notes textarea (#52)
- Repeat Last Session button on tree library page (#53)
- Auto-recovery banner for incomplete sessions (#54)
- Copy individual step to clipboard on session detail (#55)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: add missing delete button to table and list tree views

The onDeleteTree prop was accepted but never used in TreeTableView and
TreeListView. Now both views show a trash icon (permission-gated) matching
the existing grid view behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/TreeNavigationPage.tsx

@@ -4,15 +4,18 @@ import { treesApi } from '@/api/trees'
 import { sessionsApi } from '@/api/sessions'
 import { useTreeNavigationShortcuts } from '@/hooks/useKeyboardShortcuts'
 import { useCustomStepFlow } from '@/hooks/useCustomStepFlow'
+import { useSessionTimer } from '@/hooks/useSessionTimer'
 import type { Tree, Session, DecisionRecord, TreeStructure } from '@/types'
-import { cn, safeGetItem } from '@/lib/utils'
+import { cn, safeGetItem, safeSetItem } from '@/lib/utils'
 import { MarkdownContent } from '@/components/ui/MarkdownContent'
 import { CustomStepModal } from '@/components/step-library/CustomStepModal'
 import { PostStepActionModal, ContinuationModal, ForkTreeModal, ScratchpadSidebar } from '@/components/session'
-import { Plus, CheckCircle, ArrowRight } from 'lucide-react'
+import { Plus, CheckCircle, ArrowRight, Clock } from 'lucide-react'
 
 interface LocationState {
   sessionId?: string
+  prefillClientName?: string
+  prefillTicketNumber?: string
 }
 
 export function TreeNavigationPage() {
@@ -31,11 +34,14 @@ export function TreeNavigationPage() {
   const [error, setError] = useState<string | null>(null)
   const [isCompleting, setIsCompleting] = useState(false)
 
-  // Session metadata
-  const [ticketNumber, setTicketNumber] = useState<string>('')
-  const [clientName, setClientName] = useState<string>('')
+  // Session metadata (prefill from Repeat Last Session)
+  const [ticketNumber, setTicketNumber] = useState<string>(locationState?.prefillTicketNumber || '')
+  const [clientName, setClientName] = useState<string>(locationState?.prefillClientName || '')
   const [showMetadataForm, setShowMetadataForm] = useState(true)
 
+  // Session timer
+  const timerDisplay = useSessionTimer(session?.started_at)
+
   // Scratchpad state
   const [scratchpadOpen, setScratchpadOpen] = useState(() => {
     return safeGetItem('scratchpad-collapsed') === 'false'
@@ -120,6 +126,13 @@ export function TreeNavigationPage() {
       })
       setSession(newSession)
       setShowMetadataForm(false)
+      // Save for "Repeat Last Session"
+      safeSetItem('last-session', JSON.stringify({
+        tree_id: tree.id,
+        tree_name: tree.name,
+        client_name: clientName || '',
+        ticket_number: ticketNumber || '',
+      }))
     } catch (err) {
       setError('Failed to start session')
       console.error(err)
@@ -368,7 +381,15 @@ export function TreeNavigationPage() {
       {/* Header */}
       <div className="mb-6 flex items-center justify-between">
         <div>
-          <h1 className="text-xl font-bold text-white">{tree.name}</h1>
+          <div className="flex items-center gap-3">
+            <h1 className="text-xl font-bold text-white">{tree.name}</h1>
+            {timerDisplay && (
+              <span className="flex items-center gap-1 text-sm text-white/40">
+                <Clock className="h-3.5 w-3.5" />
+                {timerDisplay}
+              </span>
+            )}
+          </div>
           {(ticketNumber || clientName) && (
             <p className="text-sm text-white/40">
               {ticketNumber && `Ticket: ${ticketNumber}`}
@@ -665,6 +686,7 @@ export function TreeNavigationPage() {
             Notes (optional)
           </label>
           <textarea
+            id="session-notes"
             value={notes}
             onChange={(e) => setNotes(e.target.value)}
             placeholder="Add any notes for this step..."
@@ -698,6 +720,7 @@ export function TreeNavigationPage() {
             {(currentNode.type === 'action' || currentNode.type === 'solution') && (
               <span>, Enter {currentNode.type === 'solution' ? 'complete' : 'continue'}</span>
             )}
+            <span>, Tab notes</span>
           </div>
         )}
       </div>