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>

lib/core/documents/__tests__/document-service.test.ts

@@ -74,7 +74,7 @@ describe('uploadDocument', () => {
 
     const supabase = makeClient()
     const buffer = new TextEncoder().encode('test content').buffer
-    const result = await uploadDocument(supabase as never, 'user-1', {
+    const result = await uploadDocument(supabase as never, 'user-1', 'company-1', {
       name: 'test.pdf',
       buffer: buffer as ArrayBuffer,
       type: 'application/pdf',
@@ -87,6 +87,7 @@ describe('uploadDocument', () => {
       expect.objectContaining({
         document: expect.objectContaining({ id: 'doc-1' }),
         userId: 'user-1',
+        companyId: 'company-1',
       })
     )
   })

lib/core/documents/document-service.ts

@@ -57,6 +57,7 @@ export async function computeSHA256(buffer: ArrayBuffer): Promise<string> {
 export async function uploadDocument(
   supabase: SupabaseClient,
   userId: string,
+  companyId: string,
   file: { name: string; buffer: ArrayBuffer; type?: string },
   metadata: {
     upload_source?: DocumentUploadSource
@@ -116,7 +117,7 @@ export async function uploadDocument(
 
   await eventBus.emit({
     type: 'document.uploaded',
-    payload: { document: result, userId },
+    payload: { document: result, userId, companyId },
   })
 
   return result
@@ -192,7 +193,7 @@ export async function createNewVersion(
  */
 export async function linkToJournalEntry(
   supabase: SupabaseClient,
-  userId: string,
+  companyId: string,
   documentId: string,
   journalEntryId: string,
   journalEntryLineId?: string
@@ -205,7 +206,7 @@ export async function linkToJournalEntry(
       journal_entry_line_id: journalEntryLineId || null,
     })
     .eq('id', documentId)
-    .eq('user_id', userId)
+    .eq('company_id', companyId)
     .select()
     .single()
 
@@ -221,7 +222,7 @@ export async function linkToJournalEntry(
  */
 export async function verifyIntegrity(
   supabase: SupabaseClient,
-  userId: string,
+  companyId: string,
   documentId: string
 ): Promise<{ valid: boolean; storedHash: string; computedHash: string }> {
 
@@ -230,7 +231,7 @@ export async function verifyIntegrity(
     .from('document_attachments')
     .select('storage_path, sha256_hash')
     .eq('id', documentId)
-    .eq('user_id', userId)
+    .eq('company_id', companyId)
     .single()
 
   if (docError || !doc) {