feat: Implement core application structure, AI extraction, persistence, and Telegram bot modules with updated configuration and dependencies.

app/ai/confidence.py

@@ -0,0 +1,16 @@
+"""
+Functions for calculating confidence scores.
+"""
+
+def calculate_confidence(extracted_data: dict) -> float:
+    """
+    Calculates a confidence score based on the quality of the extracted data.
+    Stub function.
+    """
+    score = 1.0
+    # Lower score if key fields are missing
+    if not extracted_data.get("amount"):
+        score -= 0.5
+    if not extracted_data.get("description"):
+        score -= 0.3
+    return max(0.0, score)