Fix mobile layouts, sidebar actions, and thread titles

[comfuture]

Summary

• constrain the dashboard and Settings shells to the live mobile viewport and keep scrolling inside their intended content regions
• simplify the landing and project sidebar UI, restore project-row new-thread navigation, and move the responsive update action beside Settings
• use the first user message as the initial thread title, normalize Markdown mention links to plain text, and honor late thread/name/updated events for project and projectless chats

Why

The landing page clipped its voice companion description on common mobile heights, while Settings allowed scroll chaining beyond its content and could leave later screens constrained to a stale viewport height. Project rows also diverged from the expected new-thread behavior. Separately, generated app-server thread names could arrive after the live turn lifecycle subscription stopped observing them, leaving the optimistic first-message title or New Chat persisted indefinitely.

Validation

• corepack pnpm --filter @codori/client test (566 tests)
• corepack pnpm --filter @codori/client lint
• corepack pnpm --filter @codori/client typecheck
• corepack pnpm --filter @codori/client build
• mobile browser checks at 390x664 for landing and Settings scroll boundaries