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>

messages/en.json

@@ -130,6 +130,8 @@
     "ext_invoice_inbox": "Document inbox"
   },
   "agentKnowledge": {
+    "load_error_title": "Couldn't load the knowledge profile",
+    "load_error_description": "Something went wrong loading what your agent knows. Try reopening this tab.",
     "title": "What your agent knows",
     "description": "How your company books, derived from your own accounting. This is the context your assistant reads before categorizing or creating vouchers.",
     "meta_window": "Period",

messages/sv.json

@@ -130,6 +130,8 @@
     "ext_invoice_inbox": "Dokumentinkorg"
   },
   "agentKnowledge": {
+    "load_error_title": "Kunde inte läsa in kunskapsprofilen",
+    "load_error_description": "Något gick fel när det din agent vet skulle läsas in. Försök öppna fliken igen.",
     "title": "Vad din agent vet",
     "description": "Så här bokför ditt företag, härlett ur din egen bokföring. Det här är sammanhanget din assistent läser innan den kategoriserar eller skapar verifikationer.",
     "meta_window": "Period",