refacto: Adding i18n support with FR and EN as base

frontend/locales/en.json

@@ -0,0 +1,56 @@
+{
+  "app": {
+    "title": "Pharmaco Kinetics",
+    "version": "v1.00 • Dr Georges Mion"
+  },
+  "nav": {
+    "mode_esk": "ESKETAMINE",
+    "mode_rac": "RACEMIC",
+    "calculator": "Calculator",
+    "export_pdf": "Export PDF",
+    "raz": "Reset"
+  },
+  "patient": {
+    "title": "Patient Parameters",
+    "weight": "Weight (kg)",
+    "age": "Age (years)",
+    "height": "Height (cm)",
+    "concentration": "Drug Concentration (mg/mL)"
+  },
+  "models": {
+    "title": "PK Models"
+  },
+  "timeline": {
+    "title": "Chronological Dosing & Infusion (0 - 300 min)",
+    "scroll_hint": "Horizontal scroll 👉",
+    "bolus": "Bolus (mg)",
+    "perf": "Infusion (mg/kg/h)"
+  },
+  "calculator": {
+    "title": "Calculator & Dose Conversions",
+    "patient_weight": "Patient Weight",
+    "drug_conc": "Concentration",
+    "bolus_header": "Bolus Conversion",
+    "total_dose": "Total Dose (mg)",
+    "relative_dose": "Relative Dose (mg/kg)",
+    "infusion_header": "Infusion Conversion",
+    "rate_mgkgh": "Rate (mg/kg/h)",
+    "rate_ugkgmin": "Rate (µg/kg/min)"
+  },
+  "zones": {
+    "inactive": "Inactive",
+    "anti_hyperalgesic": "Anti-Hyperalgesic",
+    "analgesia": "Analgesia",
+    "psychedelic": "Psychedelic",
+    "emergence": "Emergence",
+    "narcosis": "Narcosis",
+    "excessive": "Excessive"
+  },
+  "pdf": {
+    "title": "KetaPK - Pharmacokinetic Simulation Report",
+    "date": "Simulation Date: ",
+    "mode": "Selected Mode: ",
+    "patient_info": "Patient: Weight {weight} kg | Age {age} yrs | Height {height} cm",
+    "disclaimer": "Generated by KetaPK Web. For educational purposes only."
+  }
+}