Module confidence 

Ebbinghaus forgetting-curve confidence engine.

Formula:

confidence(t) = base * exp(-lambda * elapsed_days)
             + access_bonus * ln(1 + access_count)
             + feedback_sum          // clamped to [-1, 1]

Defaults: lambda = 0.05 / day, access_bonus = 0.1.

Structs

ConfidenceEngine

Implements the Ebbinghaus forgetting-curve confidence formula.

ConfidenceParams

Tuneable parameters for the confidence formula.