feat: Hotfix Part1 - Backend support for company postal code, service tiers, timesheet naming

- Add postal_code column to companies table
- Add pricing_tiers column to services table for tiered pricing
- Update timesheet upload to generate filename in format {firstname}-{lastname}-timesheet-{date}

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/db/migrations/0008_add_company_postal_code.sql

@@ -0,0 +1,2 @@
+-- Add postal_code column to companies table
+ALTER TABLE "companies" ADD COLUMN IF NOT EXISTS "postal_code" text;

src/db/migrations/0009_add_service_pricing_tiers.sql

@@ -0,0 +1,2 @@
+-- Add pricing_tiers column to services table for tiered pricing
+ALTER TABLE "services" ADD COLUMN IF NOT EXISTS "pricing_tiers" text;