[codex] Shorten chat thread titles to four words

[gabrielMalonso]

Summary

• shorten auto-generated chat thread titles to compact 2-4 word labels
• share thread title fallback and sanitization logic across web and server
• add a small scripts/setup-worktree.sh helper to bootstrap a fresh worktree before running bun dev

Why

Thread names were still reading like mini summaries, which made the sidebar noisy and harder to scan. The goal here is to make thread names behave more like compact task labels.

Impact

• new threads now get shorter optimistic titles in the UI
• model-generated thread titles are constrained more aggressively before they hit the sidebar
• fresh worktrees get a simple bootstrap script for installing dependencies and preparing local state

Testing

• bun fmt
• bun lint (passes with one pre-existing warning in apps/web/src/environments/runtime/catalog.test.ts)
• bun typecheck
• bun run test src/chatThreads.test.ts in packages/shared
• bun run test src/git/Prompts.test.ts src/git/Layers/CodexTextGeneration.test.ts src/git/Layers/ClaudeTextGeneration.test.ts src/orchestration/Layers/ProviderCommandReactor.test.ts in apps/server

[gabrielMalonso]

Fechando sem mergear. A mudanca entrega valor, mas o footprint no core e o custo de manutencao para sync com upstream ficaram maiores do que o desejado para esta feature agora. Vamos deixar essa ideia de lado por enquanto e, se fizer sentido depois, reabrir em uma versao mais cirurgica.