feat(l1): real L1 dashboard with empty-state + resume widget

Replaces the T20 stub. L1 dashboard renders greeting, "Describe the
problem" intake card (autofocus textarea, optional customer fields,
primary "Start walk" CTA), open-tickets queue (Phase 1: display-only),
and a "Resume in progress" widget listing the L1's active sessions
ordered by last_step_at DESC. Empty-state card shows on accounts with
no queue + no active sessions (first-run nudge to upload KB or auth flows).

Adds /api/l1.ts (full L1 API client surface) and /types/l1.ts.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/l1/EmptyStateCard.tsx

@@ -0,0 +1,35 @@
+import { usePermissions } from '@/hooks/usePermissions'
+
+interface Props {
+  onUploadClick?: () => void
+}
+
+export function EmptyStateCard({ onUploadClick }: Props) {
+  const { canCoverL1 } = usePermissions()
+
+  return (
+    <div className="rounded-lg border border-default bg-card p-6">
+      <h2 className="font-heading text-xl font-bold text-heading mb-2">
+        Your knowledge base is empty
+      </h2>
+      <p className="text-muted-foreground mb-4">
+        L1 Workspace works best when your account has KB content or authored flows.
+        Right now there's nothing to match against — calls will start as ad-hoc walks.
+      </p>
+      {canCoverL1 && onUploadClick ? (
+        <button
+          type="button"
+          onClick={onUploadClick}
+          className="rounded-md bg-accent text-white px-4 py-2 text-sm font-medium hover:bg-accent/90 transition-colors"
+        >
+          Upload KB content
+        </button>
+      ) : (
+        <ul className="text-sm text-muted-foreground space-y-1 ml-4 list-disc">
+          <li>Ask your admin to upload KB documents</li>
+          <li>Or ask them to author a flow in the Flows library</li>
+        </ul>
+      )}
+    </div>
+  )
+}

frontend/src/components/l1/ResumeInProgress.tsx

@@ -0,0 +1,49 @@
+import { useEffect, useState } from 'react'
+import { Link } from 'react-router-dom'
+import { l1Api } from '@/api/l1'
+import type { WalkSession } from '@/types/l1'
+
+export function ResumeInProgress() {
+  const [sessions, setSessions] = useState<WalkSession[] | null>(null)
+
+  useEffect(() => {
+    l1Api
+      .listActiveSessions()
+      .then(setSessions)
+      .catch(() => setSessions([]))
+  }, [])
+
+  if (!sessions || sessions.length === 0) return null
+
+  return (
+    <section>
+      <div className="flex items-center gap-3 mb-3">
+        <span className="font-sans text-[0.625rem] uppercase tracking-[0.12em] font-semibold text-muted-foreground">
+          Resume in progress · {sessions.length}
+        </span>
+        <div className="flex-1 h-px bg-border" />
+      </div>
+      <div className="rounded-lg border border-default bg-card overflow-hidden">
+        {sessions.map((s) => (
+          <Link
+            key={s.id}
+            to={`/l1/walk/${s.id}`}
+            className="flex items-center justify-between px-4 py-3 hover:bg-elevated transition-colors border-b border-default last:border-b-0"
+          >
+            <div className="flex items-center gap-3">
+              <span className="font-mono text-xs text-muted-foreground">#{s.id.slice(0, 8)}</span>
+              <span className="text-sm">
+                {s.session_kind === 'adhoc'
+                  ? `Ad-hoc · ${s.walk_notes.length} notes`
+                  : `Step ${s.walked_path.length}`}
+              </span>
+            </div>
+            <span className="text-xs text-muted-foreground">
+              {new Date(s.last_step_at).toLocaleTimeString()}
+            </span>
+          </Link>
+        ))}
+      </div>
+    </section>
+  )
+}