Client-side writing panel for DeepSeek Harness

Key features

• Hang at the bottom of the sidebar, four tabs.
• In the "writing" preset session, there's an index next to the "dialogue/trajection" top
• Only the sessions that are preset for "writing" (agentPreset = = "writing") display panel and index views, with other sessions completely invisible.
• ItemVolume/chapter table of contents (words, status, summary)
• Book-wide statistics (chapters/total words/unrecovered pens/enabled records)