feat: API key settings page — store ANTHROPIC/VOYAGE keys in DB with admin UI

- Migration: app_settings table with admin-only RLS (ANTHROPIC_API_KEY, VOYAGE_API_KEY)
- lib/settings.ts: getApiKey() reads DB first, falls back to env var
- lib/claude/client.ts: factory createAnthropicClient(apiKey) replaces singleton
- lib/claude/embed.ts: optional apiKey param, falls back to env
- 3 Claude AI routes + similar route: fetch key from settings before calling AI
- incidents/route.ts: fire-and-forget embed reads VOYAGE key from settings
- GET/POST /api/settings: admin-only masked key management endpoint
- /hse/settings page + ApiKeyForm client component

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FFDuBhMKvoWjrWT3ZnGmmr

app/api/settings/route.ts

@@ -0,0 +1,65 @@
+export const dynamic = 'force-dynamic'
+
+import { NextRequest, NextResponse } from 'next/server'
+import { createClient } from '@/lib/supabase/server'
+
+const ALLOWED_KEYS = ['ANTHROPIC_API_KEY', 'VOYAGE_API_KEY'] as const
+type SettingKey = typeof ALLOWED_KEYS[number]
+
+async function requireAdmin(supabase: Awaited<ReturnType<typeof createClient>>) {
+  const { data: { user }, error } = await supabase.auth.getUser()
+  if (error || !user) return null
+  const { data: profile } = await supabase.from('users').select('role').eq('id', user.id).single()
+  if (!profile || profile.role !== 'admin') return null
+  return user
+}
+
+export async function GET() {
+  const supabase = await createClient()
+  const user = await requireAdmin(supabase)
+  if (!user) return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
+
+  const { data } = await supabase.from('app_settings').select('key, value, updated_at')
+  const masked = (data ?? []).map(row => ({
+    key: row.key,
+    set: Boolean(row.value),
+    masked_value: row.value ? `${row.value.slice(0, 8)}${'•'.repeat(12)}` : '',
+    updated_at: row.updated_at,
+  }))
+  return NextResponse.json(masked)
+}
+
+export async function POST(request: NextRequest) {
+  const supabase = await createClient()
+  const user = await requireAdmin(supabase)
+  if (!user) return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
+
+  let body: { key?: string; value?: string }
+  try { body = await request.json() } catch {
+    return NextResponse.json({ error: 'Invalid JSON' }, { status: 400 })
+  }
+
+  if (!body.key || !ALLOWED_KEYS.includes(body.key as SettingKey)) {
+    return NextResponse.json({ error: 'Invalid key' }, { status: 422 })
+  }
+  if (typeof body.value !== 'string') {
+    return NextResponse.json({ error: 'value required' }, { status: 422 })
+  }
+
+  const { error } = await supabase.from('app_settings').upsert({
+    key: body.key,
+    value: body.value,
+    updated_at: new Date().toISOString(),
+    updated_by: user.id,
+  })
+  if (error) return NextResponse.json({ error: 'Save failed' }, { status: 500 })
+
+  await supabase.rpc('write_audit_log', {
+    p_table_name: 'app_settings',
+    p_record_id: user.id,
+    p_action: 'UPDATE',
+    p_new_value: { key: body.key, set: Boolean(body.value) } as never,
+  })
+
+  return NextResponse.json({ ok: true })
+}