fix(classification): restore service logic and standardization formula

- Restored missing method implementations in ClassificationService (classify, extract_metrics)
- Fixed Standardization Logic not being applied in metric cascade
- Bumped version to v0.7.4 in config.py
- Removed duplicate API endpoint in app.py
- Updated MIGRATION_PLAN.md

MIGRATION_PLAN.md

@@ -94,6 +94,13 @@ Wir kapseln das neue Projekt vollständig ab ("Fork & Clean").
 
 ## 7. Historie & Fixes (Jan 2026)
 
+    *   **[CRITICAL] v0.7.4: Service Restoration & Logic Fix (Jan 24, 2026)**
+        *   **Summary:** Identified and resolved a critical issue where `ClassificationService` contained empty placeholder methods, leading to "Others" classification and missing metrics.
+        *   **Fixes Implemented:**
+            *   **Service Restoration:** Completely re-implemented `classify_company_potential`, `_run_llm_classification_prompt`, and `_run_llm_metric_extraction_prompt` to restore AI functionality.
+            *   **Standardization Logic:** Connected the `standardization_logic` formula parser (e.g., "Values * 100m²") into the metric extraction cascade. It now correctly computes `standardized_metric_value` (e.g., 352 beds -> 35,200 m²).
+            *   **Verification:** Confirmed end-to-end flow from "New Company" -> "Healthcare - Hospital" -> "352 Betten" -> "35200 m²" via the UI "Play" button.
+
     *   **[STABILITY] v0.7.3: Hardening Metric Parser & Regression Testing (Jan 23, 2026) [RESOLVED]**
         *   **Summary:** A series of critical fixes were applied to the `MetricParser` to handle complex real-world scenarios, and a regression test suite was created to prevent future issues.
         *   **Fixes Implemented:**