feat(l1): frontend api/types for next-node, intake outcome, categories

Add IntakeOutcome/IntakeResult/NearMiss, TreeNode union, NextNodeRequest/Result,
L1Categories types; add ai_build to SessionKind; retype intake() to IntakeResult and
add nextNode/escalations/getCategories/setCategories methods. nextNode body carries
node_text (backend advance_ai_build stores it). tsc -b clean.

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

frontend/src/api/l1.ts

@@ -1,7 +1,10 @@
 import { apiClient } from './client'
 import type {
   IntakeRequest,
-  IntakeResponse,
+  IntakeResult,
+  L1Categories,
+  NextNodeRequest,
+  NextNodeResult,
   QueueRow,
   WalkSession,
   AdhocNote,
@@ -9,7 +12,23 @@ import type {
 
 export const l1Api = {
   intake: (body: IntakeRequest) =>
-    apiClient.post<IntakeResponse>('/l1/intake', body).then(r => r.data),
+    apiClient.post<IntakeResult>('/l1/intake', body).then(r => r.data),
+
+  nextNode: (sessionId: string, body: NextNodeRequest) =>
+    apiClient
+      .post<NextNodeResult>(`/l1/sessions/${sessionId}/next-node`, body)
+      .then(r => r.data),
+
+  escalations: () =>
+    apiClient.get<WalkSession[]>('/l1/escalations').then(r => r.data),
+
+  getCategories: () =>
+    apiClient.get<L1Categories>('/accounts/me/l1-categories').then(r => r.data),
+
+  setCategories: (enabled: string[]) =>
+    apiClient
+      .patch<L1Categories>('/accounts/me/l1-categories', { enabled })
+      .then(r => r.data),
 
   queue: (statusFilter?: string) =>
     apiClient.get<QueueRow[]>('/l1/queue', {