fix: summarize single daily exchanges

[vycdev2]

Summary

• Generate a Claude daily summary when a channel has one complete user-and-bot exchange.
• Keep the existing raw-log fallback for empty or single-line logs.
• Add regression coverage and an Unreleased changelog entry.

Verification

• npm ci — passed; npm reported 13 existing audit vulnerabilities and a pending node-pty install-script approval warning.
• npm run build — passed.
• node --test tests/summaryWorkload.test.mjs — passed (2 tests).
• npm test — passed (66 tests).
• Direct node-pty import probe — passed.
• git diff --check upstream/main...HEAD — passed.
• TDD RED: the new focused test failed before the fix because two-line logs were copied without invoking the summary runner; GREEN passed after changing the minimum meaningful log to two lines.

Risk

Low. This only changes the daily-summary threshold from three lines to two, allowing one complete exchange to be summarized; empty and one-line logs retain their existing fallback behavior.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.