[REM] website_sale_aplicoop: remove dead code and orphaned tests

Duplicate _translate_labels fallback, unreachable /eskaera/add-to-cart and
/eskaera/save-cart routes (the frontend cart is localStorage-only and uses
save-order), redundant pickup wrappers, unused pagination/count helpers and
fields, deprecated JS shims, and the already-empty checkout_summary.js and
i18n key/init leftovers.

Also drops 11 tests/*.py never wired into tests/__init__.py: three were
unimplemented placeholders (setUp with no assertions), and the other eight
had real assertions but were bit-rotted against the current schema (e.g.
res.partner.is_supplier no longer exists) — wiring them in surfaced 43
failures unrelated to this cleanup. Verified 0 failed/0 errors of 270 tests
both before and after.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

website_sale_aplicoop/__manifest__.py

@@ -60,10 +60,6 @@
         # Demo: Sale Orders
         "demo/sale_order_demo.xml",
     ],
-    "i18n": [
-        "i18n/es.po",
-        "i18n/eu_ES.po",
-    ],
     "external_dependencies": {
         "python": [],
     },
@@ -77,7 +73,6 @@
             "website_sale_aplicoop/static/src/js/website_sale.js",
             "website_sale_aplicoop/static/src/js/checkout_labels.js",
             "website_sale_aplicoop/static/src/js/home_delivery.js",
-            "website_sale_aplicoop/static/src/js/checkout_summary.js",
             "website_sale_aplicoop/static/src/js/eskaera_payment.js",
             # Search and pagination
             "website_sale_aplicoop/static/src/js/infinite_scroll.js",