Improve conversation title generation for multi-tab workflows

Problem

When working across multiple Claude Code sessions in VS Code tabs, conversation titles frequently don't reflect the primary topic or output of the session. Current titles appear to be generated from the first user prompt, which is often a vague opener (e.g., "What's next on my TODOs?") rather than a description of what the session actually accomplished (e.g., "Timed Conditioning Program Design and TODO Review").

This makes it difficult to:

• Relocate a specific conversation when picking up work from a TODO or note
• Distinguish between tabs when multiple sessions are open simultaneously
• Review past conversations for context on prior decisions

In practice, I end up opening 3-5 candidate sessions before finding the right one.

Proposed Solution

1. Context-aware auto-titling: Generate titles based on the full conversation arc (primary topic, key deliverables, files modified) rather than just the first prompt. Re-evaluate the title as the conversation progresses.
2. User-editable titles: Allow manual rename of conversation titles via right-click on the tab or a rename action in the chat history panel. Persist the user-set title so it survives restarts.

Alternatives Considered

• Searchable chat history: A search/filter across all conversations (by keyword, date, file touched) would reduce dependence on titles. Complementary to better titles, not a replacement.
• Tagging or pinning: Let users tag conversations with project names or pin important ones. Useful but higher complexity.
• Summary record in JSONL: Storing a type: "summary" record in the conversation JSONL file that the UI reads. Investigated this approach manually; the VS Code extension currently generates titles at runtime and does not read stored summary fields.

Context

• VS Code extension, multi-tab usage pattern
• Typical workflow: 5-15 active sessions per week across 2-3 projects
• Current title generation appears to use first user message or a truncated version of it