feat: multi-tenant company refactor (GNU-19) (#153)

* feat: multi-tenant company refactor (GNU-19)

Introduce companies table, company_members, and user_preferences to
support multiple companies per user. All data scoping changes from
user_id to company_id across the entire codebase.

Key changes:
- Database migration: new tables, company_id on 40+ tables, backfill,
  RLS rewrite from user_id to company-member-based, updated RPCs
- Types: Company, CompanyMember, CompanyRole, UserPreferences types;
  company_id added to all entity interfaces; companyId on all events
- Engine: all 7 core functions take companyId; storno, period, year-end
  services updated; 16 report generators updated
- Middleware: company context resolution (cookie → prefs → first company)
- API routes: ~120 routes updated with requireCompanyId()
- Frontend: CompanyProvider context, layout/dashboard/onboarding updated
- Extensions: context factory, 9 extensions, all lib files updated
- Tests: 1880 tests passing, all helpers updated with company_id defaults

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

* feat: add database migrations for multi-tenant company and team system (GNU-19)

Adds company_invitations, company creation RPC, team_members, account
deletion RPC, and teams table refactor migrations. Updates base
multi-tenant migration with cascading FKs and onboarding_step column.

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

* feat: add team types and update core infrastructure for multi-tenancy (GNU-19)

Adds TeamRole, MemberSource, and Team types. Refactors Supabase service
client to be stateless, updates middleware for team-aware routing, extends
CompanyContext with team/role fields, and updates extension service types
to accept companyId.

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

* refactor: thread company_id through business logic functions (GNU-19)

Replaces user_id scoping with company_id across all lib modules:
bookkeeping, documents, transactions, invoices, reconciliation, tax,
deadlines, and import. Updates corresponding tests.

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

* refactor: thread company_id through API routes and extensions (GNU-19)

Updates all existing API routes to extract and pass companyId. Updates
enable-banking and arcim-migration extensions for company-scoped
transaction ingestion and sync.

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

* feat: add company and team management API routes (GNU-19)

Adds CRUD endpoints for company members, company invitations, team
members, and team invitations. Includes invite token utilities, email
templates, and company switch server action.

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

* feat: add team/company UI components, pages, and dashboard updates (GNU-19)

Adds CompanySwitcher, ConsultantEmptyState, Step0RoleChoice, company
members and team management panels. Updates dashboard layout for
team-aware routing, onboarding for multi-step role choice, and auth
callback for team invite acceptance. Ignores supabase/.branches/.

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

* fix: add null guards for company in import page (GNU-19)

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

* fix: move appUrl declaration to outer scope in invite route (GNU-19)

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

* fix: add optional chaining for company.name in members section (GNU-19)

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

* fix: add optional chaining for second company.name in members section (GNU-19)

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

* fix: add null guards for company in extension components (GNU-19)

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

* fix: pass companyId to executeSIEImport in arcim-migration extension (GNU-19)

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

* fix: update tests to use companyId instead of userId and improve type handling

---------

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

app/api/settings/api-keys/[id]/route.ts

@@ -1,5 +1,6 @@
 import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
+import { requireCompanyId } from '@/lib/company/context'
 
 /**
  * DELETE /api/settings/api-keys/[id] — Revoke an API key (soft delete)
@@ -16,11 +17,13 @@ export async function DELETE(
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
+  const companyId = await requireCompanyId(supabase, user.id)
+
   const { error } = await supabase
     .from('api_keys')
     .update({ revoked_at: new Date().toISOString() })
     .eq('id', id)
-    .eq('user_id', user.id)
+    .eq('company_id', companyId)
     .is('revoked_at', null)
 
   if (error) {

app/api/settings/api-keys/route.ts

@@ -1,6 +1,7 @@
 import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
 import { generateApiKey, hashApiKey, DEFAULT_SCOPES, validateScopes } from '@/lib/auth/api-keys'
+import { requireCompanyId } from '@/lib/company/context'
 import type { ApiKeyScope } from '@/lib/auth/api-keys'
 
 /**
@@ -14,10 +15,12 @@ export async function GET() {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
+  const companyId = await requireCompanyId(supabase, user.id)
+
   const { data, error } = await supabase
     .from('api_keys')
     .select('id, key_prefix, name, scopes, rate_limit_rpm, last_used_at, revoked_at, created_at')
-    .eq('user_id', user.id)
+    .eq('company_id', companyId)
     .order('created_at', { ascending: false })
 
   if (error) {
@@ -39,6 +42,8 @@ export async function POST(request: Request) {
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
+  const companyId = await requireCompanyId(supabase, user.id)
+
   let name = 'Unnamed key'
   let scopes: ApiKeyScope[] = DEFAULT_SCOPES
   try {
@@ -54,11 +59,11 @@ export async function POST(request: Request) {
     // Empty body is fine, use defaults
   }
 
-  // Limit to 10 active keys per user
+  // Limit to 10 active keys per company
   const { count } = await supabase
     .from('api_keys')
     .select('id', { count: 'exact', head: true })
-    .eq('user_id', user.id)
+    .eq('company_id', companyId)
     .is('revoked_at', null)
 
   if (count !== null && count >= 10) {
@@ -74,6 +79,7 @@ export async function POST(request: Request) {
     .from('api_keys')
     .insert({
       user_id: user.id,
+      company_id: companyId,
       key_hash: hash,
       key_prefix: prefix,
       name,