refactor: implement i18n in MetodologiaDrawer (phase 4)

Refactored MetodologiaDrawer to use react-i18next translations:
- All 8 subsections (DataSummary, Pipeline, Taxonomy, KPI, CPI, BeforeAfter, SkillsMapping, Guarantees)
- 100+ text strings replaced with t() calls
- Month names in date formatting

Added translation keys to es.json and en.json:
- methodology section with 40+ new keys
- CPI calculation components
- Impact analysis labels
- Skill mapping explanations

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https://claude.ai/code/session_4f888c33-8937-4db8-8a9d-ddc9ac51a725

frontend/locales/en.json

@@ -713,6 +713,10 @@
     "monthsHistory": "Months of history",
     "sourceSystem": "Source system",
     "periodRange": "Period: {{period}}",
+    "defaultPeriod": "January - December 2025",
+    "sourceGenesys": "Genesys Cloud CX",
+    "sourceDataset": "Loaded dataset",
+    "pdfDevelopment": "PDF download functionality under development. The document will be available soon.",
     "pipeline": {
       "title": "Transformation Pipeline",
       "description": "Modular 3-layer architecture to ensure traceability and scalability.",
@@ -771,6 +775,21 @@
       "howCalculate": "How is Total Cost calculated?",
       "costEquals": "Cost ="
     },
+    "cpi": {
+      "description": "CPI is calculated by dividing <strong>total cost</strong> by <strong>interaction volume</strong>. Total cost includes <em>all</em> interactions (noise, zombie, and valid) because all are billed, and applies a productivity factor of {{productivity}}%.",
+      "volume": "Volume",
+      "ahtExplanation": "The <strong>AHT</strong> is in seconds, converted to hours by dividing by 3600. Includes all interactions that generate cost (noise + zombie + valid). Only abandons are excluded because they don't consume agent time.",
+      "hourlyRate": "Agent Hourly Rate (Fully Loaded)",
+      "configuredValue": "Configured value: €{{value}}/h",
+      "includesAllCosts": "This value was configured in the data input screen and should include all costs associated with the agent:",
+      "cost1": "Agent gross salary",
+      "cost2": "Social security costs",
+      "cost3": "Software licenses",
+      "cost4": "Infrastructure and workstation",
+      "cost5": "Supervision and QA",
+      "cost6": "Training and overhead",
+      "adjustNote": "If you need to adjust this value, you can return to the data input screen and modify it."
+    },
     "impact": {
       "title": "Transformation Impact",
       "metric": "Metric",
@@ -784,12 +803,18 @@
       "revealsDemand": "Reveals hidden failed demand",
       "detectsFrustration": "Detects real customer frustration",
       "executiveVision": "Actionable executive vision",
-      "reflectsPerformance": "KPIs reflect real performance"
+      "reflectsPerformance": "KPIs reflect real performance",
+      "technicalSkills": "{{count}} technical",
+      "businessLines": "{{count}} business lines",
+      "distorted": "Distorted",
+      "clean": "Clean",
+      "withoutTransformation": "Without this transformation,",
+      "wrongInvestments": "automation decisions would be based on incorrect data, generating investments in the wrong processes."
     },
     "skillMapping": {
       "title": "Skills to Business Lines Mapping",
       "simplificationApplied": "Simplification applied",
-      "reductionDesc": "Reduced complexity from 980 technical skills to {{count}} actionable Business Lines using fuzzy keyword logic.",
+      "reductionDesc": "Reduced complexity from 980 technical skills to {{count}} Business Lines. This simplification is vital for executive visualization and strategic decision making.",
       "businessLine": "Business Line",
       "keywords": "Detected Keywords (Fuzzy Logic)",
       "baggage": "Baggage & Handling",
@@ -799,7 +824,8 @@
       "changes": "Changes & Post-Sales",
       "digital": "Digital Support",
       "customer": "Customer Service",
-      "internal": "Internal / Backoffice"
+      "internal": "Internal / Backoffice",
+      "fuzzyLogicNote": "The mapping uses fuzzy logic to automatically classify each technical skill based on keywords detected in its name. Unclassified skills are assigned to \"Customer Service\"."
     },
     "quality": {
       "title": "Quality Guarantees",