Ask any line of code its backstory

Key features

• git blame → who / when / which commit.
• dsh-backstory → what the line does + why it's here, in one place.
• Not a generic "explain this code" (any LLM does that).
• The why comes from real repository history, so the answer is grounded, not guessed.
• When the agent itself wrote a line, it adds a dsh-native origin that git blame can never give you — which turn wrote it, and your prompt — per line (t14) and for the file