Add top-level members list, primary member on account, member move, combined create flows

- GET /v1/members with search across all members (includes account name)
- POST /members/:id/move with optional accountId (creates new account if omitted)
- primary_member_id on account table, auto-set when first member added
- isMinor flag on member create (manual override when no DOB provided)
- Account search now includes member names
- New account form includes primary contact fields, auto-generates name
- Members page in sidebar with global search

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

@@ -31,6 +31,7 @@ export const accounts = pgTable('account', {
     zip?: string
   }>(),
   billingMode: billingModeEnum('billing_mode').notNull().default('consolidated'),
+  primaryMemberId: uuid('primary_member_id'),
   notes: text('notes'),
   isActive: boolean('is_active').notNull().default(true),
   legacyId: varchar('legacy_id', { length: 255 }),