VSCode extension: let users control tab titles (or revert to first-message behavior)

Problem

The VSCode extension recently changed tab titles from using the user's first message to AI-generated summaries. This broke workflows for users who relied on the old behavior to organize their sessions.

Previously, I could type a deliberate first message like pipeline: fix mockup scoring and the tab would be titled exactly that — giving me a predictable, scannable set of tabs. Now tabs get titles like "Fixing the mockup scoring threshold in the pipeline configuration" which are long, unpredictable, and harder to scan.

The conversation rename feature in the history dropdown doesn't update the actual tab title, so there's no workaround.

Proposal

One or more of:

1. Setting to revert to first-message titles — e.g. claude-code.tabTitleSource: "firstMessage" | "summary"
2. Let conversation rename update the tab title — if I rename a session in the history list, the tab title should reflect that
3. Let users manually set the tab title — a command or UI action to override the generated title

Why it matters

Power users who run multiple Claude Code sessions in parallel rely on tab titles for navigation. Predictable, user-controlled titles are essential for this workflow.