리텐션 분석 스크립트 최초 커밋

Add retention analysis configuration file
- Introduced `retention_analysis_config.json` to define settings for retention analysis.
- Configured analysis settings including correlation threshold, top features, and minimum sample size.
- Specified retention groups for analysis.
- Listed columns to be excluded from the analysis.
- Defined key metrics for day 0 analysis.
- Set output preferences for saving results in various formats.

.claude/settings.local.json

@@ -0,0 +1,11 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(python:*)",
+      "Bash(pip install:*)",
+      "Read(C:\\Users/**)"
+    ],
+    "deny": [],
+    "ask": []
+  }
+}