feat: remove AI extensions, restructure settings, and add atomic voucher commits (#157)

Remove AI-dependent extensions (ai-chat, ai-categorization, receipt-ocr,
invoice-inbox) and their infrastructure (lib/ai/*, ai-consent, LangChain/
Anthropic/OpenAI deps) to simplify core and reduce bundle size.

Restructure monolithic settings page into dedicated sub-pages (company,
bookkeeping, invoicing, tax, banking, api, account, team, templates) with
shared layout and sidebar navigation.

Add atomic commit_journal_entry RPC so voucher number increment and status
update happen in a single transaction — prevents burned numbers on constraint
failures. Add continuity check report and voucher gap explanation tracking.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

supabase/migrations/20260401200000_settings_restructure.sql

@@ -0,0 +1,40 @@
+-- Settings restructure: add bookkeeping lock, PDF/invoice settings
+-- Phase 2: Bookkeeping settings
+ALTER TABLE public.company_settings
+  ADD COLUMN IF NOT EXISTS bookkeeping_locked_through date,
+  ADD COLUMN IF NOT EXISTS auto_lock_period_days integer;
+
+-- Phase 3: Invoice/PDF settings
+ALTER TABLE public.company_settings
+  ADD COLUMN IF NOT EXISTS ore_rounding boolean DEFAULT true,
+  ADD COLUMN IF NOT EXISTS invoice_show_ocr boolean DEFAULT true,
+  ADD COLUMN IF NOT EXISTS invoice_show_bankgiro boolean DEFAULT true,
+  ADD COLUMN IF NOT EXISTS invoice_show_plusgiro boolean DEFAULT true,
+  ADD COLUMN IF NOT EXISTS invoice_late_fee_text text,
+  ADD COLUMN IF NOT EXISTS invoice_credit_terms_text text;
+
+-- Enforce company-wide bookkeeping lock date on journal entries
+CREATE OR REPLACE FUNCTION public.enforce_company_lock_date()
+RETURNS TRIGGER AS $$
+DECLARE
+  lock_date date;
+BEGIN
+  SELECT bookkeeping_locked_through INTO lock_date
+  FROM public.company_settings
+  WHERE company_id = NEW.company_id;
+
+  IF lock_date IS NOT NULL AND NEW.entry_date <= lock_date THEN
+    RAISE EXCEPTION 'Bokföringen är låst t.o.m. %. Kan inte skapa verifikation med datum %.',
+      lock_date, NEW.entry_date;
+  END IF;
+
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+-- Apply trigger only on insert and update of entry_date
+DROP TRIGGER IF EXISTS trg_enforce_company_lock_date ON public.journal_entries;
+CREATE TRIGGER trg_enforce_company_lock_date
+  BEFORE INSERT OR UPDATE OF entry_date ON public.journal_entries
+  FOR EACH ROW
+  EXECUTE FUNCTION public.enforce_company_lock_date();