redesign: rename Project→Client, finance single-card + filters, mobile tasks, sticky headers

- Rename "Project" → "Client" across UI (labels + /projects→/clients routes with redirect); normalize company-meaning labels to "Company"
- Finance tabs: merge dual cards into one per tab, add header column filters (expenses/subs/invoices), overview as 3-section card, move +Expense/+Invoice to card right edge
- Tasks: responsive mobile stats grid, progressive column hiding (min Status+Name+Assigned), sidebar mobile footer (profile/theme/signout)
- Hide Company column for single-company users; +Task shows disabled Company field instead of hiding
- Sticky table headers site-wide with opaque card background
- Pin dev server to port 5173

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

vite.config.js

@@ -4,7 +4,7 @@ import react from '@vitejs/plugin-react'
 // https://vite.dev/config/
 export default defineConfig({
   plugins: [react()],
-  server: { port: 4173 },
+  server: { port: 5173 },
   build: {
     rollupOptions: {
       output: {