feat(agent): move 'Vad din agent vet' into settings (Assistenten -> Kunskap) (#1008)

Relocates the ledger-knowledge surface off the top nav and into the
assistant settings hub as a third tab (Minne / Kompetens / Kunskap), per
the code's own "minne + kunskap under Assistenten" intent and the #935
flag that this was an easy call to change.

Because both settings surfaces (the full-page rail and the intercepting
settings modal) mount each section as a propless component via
SETTINGS_SECTIONS, the knowledge data must be fetched client-side rather
than passed as a server prop:

- New GET /api/agent/knowledge aggregates buildLedgerContext +
  buildDeepEntities + buildAgentCompetence + company name (read-only,
  company-scoped via withRouteContext).
- AgentKnowledgeView + AgentCompetenceSections converted from async
  server components to client components (getTranslations ->
  useTranslations; no other server-only usage).
- New AgentKnowledgePanel client wrapper lazy-fetches the payload when
  the Kunskap tab opens (Radix unmounts inactive tabs), with Skeleton and
  error states matching the memory/skills panels.
- Removed the Brain/agent-knowledge entry (and its now-unused import)
  from the Analys nav group.
- /agent-knowledge kept as a redirect to /settings/assistant?view=knowledge
  so old links/bookmarks resolve.

Tests: new route test (auth 401, no-company 400, happy-path aggregation).
i18n: load_error_* keys added to both locales (parity kept).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/agent-knowledge/AgentKnowledgeView.tsx

@@ -1,4 +1,6 @@
-import { getTranslations } from 'next-intl/server'
+'use client'
+
+import { useTranslations } from 'next-intl'
 import { Brain } from 'lucide-react'
 import {
   Card,
@@ -49,7 +51,7 @@ function vatLabel(code: string | null): string | null {
   return VAT_LABELS[code] ?? code
 }
 
-export async function AgentKnowledgeView({
+export function AgentKnowledgeView({
   context,
   deep,
   competence,
@@ -60,7 +62,7 @@ export async function AgentKnowledgeView({
   competence: AgentCompetence
   companyName: string
 }) {
-  const t = await getTranslations('agentKnowledge')
+  const t = useTranslations('agentKnowledge')
 
   const { meta, explicit_rules, vat_profile, conventions } = context