feat: printable receipts with barcode on payment complete

- Receipt component with thermal (80mm) and full-page layout support
- Code 128 barcode from transaction number via JsBarcode
- Store name, address, line items, totals, payment info, barcode
- Print button on sale complete screen (browser print dialog)
- Email button placeholder (disabled, ready for SMTP integration)
- @media print CSS hides everything except receipt content
- Receipt data fetched from GET /transactions/:id/receipt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bun.lock

@@ -34,6 +34,7 @@
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "date-fns": "^4.1.0",
+        "jsbarcode": "^3.12.3",
         "jspdf": "^4.2.1",
         "lucide-react": "^1.7.0",
         "radix-ui": "^1.4.3",
@@ -59,7 +60,7 @@
     },
     "packages/backend": {
       "name": "@lunarfront/backend",
-      "version": "0.0.1",
+      "version": "0.1.1",
       "dependencies": {
         "@fastify/cors": "^10",
         "@fastify/jwt": "^9",
@@ -842,6 +843,8 @@
 
     "js-yaml": ["js-yaml@4.1.1", "", { "dependencies": { "argparse": "^2.0.1" }, "bin": { "js-yaml": "bin/js-yaml.js" } }, "sha512-qQKT4zQxXl8lLwBtHMWwaTcGfFOZviOJet3Oy/xmGk2gZH677CJM9EvtfdSkgWcATZhj/55JZ0rmy3myCT5lsA=="],
 
+    "jsbarcode": ["jsbarcode@3.12.3", "", {}, "sha512-CuHU9hC6dPsHF5oVFMo8NW76uQVjH4L22CsP4hW+dNnGywJHC/B0ThA1CTDVLnxKLrrpYdicBLnd2xsgTfRnvg=="],
+
     "jsesc": ["jsesc@3.1.0", "", { "bin": { "jsesc": "bin/jsesc" } }, "sha512-/sM3dO2FOzXjKQhJuo0Q173wf2KOo8t4I8vHy6lF9poUp7bKT0/NHE8fPX23PwfhnykfqnC2xRxOnVw5XuGIaA=="],
 
     "json-buffer": ["json-buffer@3.0.1", "", {}, "sha512-4bV5BfR2mqfQTJm+V5tPPdf+ZpuhiIvTuAB5g8kcrXOZpTT/QwwVRWBywX1ozr6lEuPdbHxwaJlm9G6mI2sfSQ=="],