feat(web): add credibility strip to subscription page

The page had no credibility signal at the point of conversion. Added a
CredibilityStrip under the header (shown only to converting users:
no-sub / trial / expired / pending) surfacing real, verifiable product
facts — 50+ marka, 1M+ parça, OEM + alternatif kodlar, saniyede sonuç,
KVKK uyumlu · SSL. Deliberately no fabricated customer counts or
testimonials.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/messages/en.json

@@ -176,6 +176,13 @@
     "matrixBrandCount": "Brand count",
     "brandCountAll": "All",
     "planHelper": "Which plan should I pick? Choose the number of brands you work with. For 4+ brands, the Full Package is cheaper per brand.",
+    "credibility": {
+      "brands": "50+ brands",
+      "parts": "1M+ parts",
+      "oem": "OEM + alternative codes",
+      "speed": "Results in seconds",
+      "security": "KVKK compliant · SSL"
+    },
     "selectBrands": "Select Brands",
     "selectBrandsDescription": "Choose the brands you want to include in your plan.",
     "brandsSelected": "brands selected",

apps/web/src/messages/tr.json

@@ -176,6 +176,13 @@
     "matrixBrandCount": "Marka sayısı",
     "brandCountAll": "Tümü",
     "planHelper": "Hangi planı seçmeliyim? İşine giren marka sayısını seç. 4+ marka için Full Paket marka başına daha avantajlı.",
+    "credibility": {
+      "brands": "50+ marka",
+      "parts": "1M+ parça",
+      "oem": "OEM + alternatif kodlar",
+      "speed": "Saniyede sonuç",
+      "security": "KVKK uyumlu · SSL"
+    },
     "selectBrands": "Marka Seçin",
     "selectBrandsDescription": "Planınıza dahil etmek istediğiniz markaları seçin.",
     "brandsSelected": "marka seçildi",