Remove multi-tenant company_id scoping from entire codebase

Drop company_id column from all 22 domain tables via migration.
Remove companyId from JWT payload, auth plugins, all service method
signatures (~215 occurrences), all route handlers (~105 occurrences),
test runner, test suites, and frontend auth store/types.

The company table stays as store settings (name, timezone). Tenant
isolation in a SaaS deployment would be at the database level (one
DB per customer) not the application level.

All 107 API tests pass. Zero TSC errors across all packages.

packages/backend/src/db/schema/repairs.ts

@@ -9,7 +9,7 @@ import {
   numeric,
   pgEnum,
 } from 'drizzle-orm/pg-core'
-import { companies, locations } from './stores.js'
+import { locations } from './stores.js'
 import { accounts } from './accounts.js'
 import { inventoryUnits, products } from './inventory.js'
 import { users } from './users.js'
@@ -66,9 +66,6 @@ export const repairBatchApprovalEnum = pgEnum('repair_batch_approval', [
 // Defined before repairTickets because tickets FK to batches
 export const repairBatches = pgTable('repair_batch', {
   id: uuid('id').primaryKey().defaultRandom(),
-  companyId: uuid('company_id')
-    .notNull()
-    .references(() => companies.id),
   locationId: uuid('location_id').references(() => locations.id),
   batchNumber: varchar('batch_number', { length: 50 }),
   accountId: uuid('account_id')
@@ -97,9 +94,6 @@ export const repairBatches = pgTable('repair_batch', {
 
 export const repairTickets = pgTable('repair_ticket', {
   id: uuid('id').primaryKey().defaultRandom(),
-  companyId: uuid('company_id')
-    .notNull()
-    .references(() => companies.id),
   locationId: uuid('location_id').references(() => locations.id),
   repairBatchId: uuid('repair_batch_id').references(() => repairBatches.id),
   ticketNumber: varchar('ticket_number', { length: 50 }),
@@ -163,9 +157,6 @@ export type RepairNoteInsert = typeof repairNotes.$inferInsert
 
 export const repairServiceTemplates = pgTable('repair_service_template', {
   id: uuid('id').primaryKey().defaultRandom(),
-  companyId: uuid('company_id')
-    .notNull()
-    .references(() => companies.id),
   name: varchar('name', { length: 255 }).notNull(),
   instrumentType: varchar('instrument_type', { length: 100 }),
   size: varchar('size', { length: 50 }),