Change default IQR multiplier to 1.0 for more aggressive outlier filtering

- Change ANALYSIS_IQR_MULTIPLIER default from 1.5 to 1.0 in config.py
- Add iqr_multiplier parameter to all filtering & statistics functions
- Allow runtime override via MCP tools (get_valuation_comparables, get_deal_statistics)
- Update CLAUDE.md docs with new default & override examples

Rationale: k=1.0 catches more suspicious deals (e.g. 43% below median) while
still preserving legitimate edge cases via hard bounds. Users can override
per-call for more conservative filtering (k=1.5) if needed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

nadlan_mcp/config.py

@@ -61,7 +61,7 @@ class GovmapConfig:
         default_factory=lambda: os.getenv("ANALYSIS_OUTLIER_METHOD", "iqr")
     )
     analysis_iqr_multiplier: float = field(
-        default_factory=lambda: float(os.getenv("ANALYSIS_IQR_MULTIPLIER", "1.5"))
+        default_factory=lambda: float(os.getenv("ANALYSIS_IQR_MULTIPLIER", "1.0"))
     )
     analysis_min_deals_for_outlier_detection: int = field(
         default_factory=lambda: int(os.getenv("ANALYSIS_MIN_DEALS_FOR_OUTLIER_DETECTION", "10"))