Sync Threadleaf titles to Codex sessions

[windzu]

What changed

• Added a provider-neutral optional session-title capability to the chat runtime.
• Mapped the Codex runtime implementation to thread/name/set.
• Synced the Threadleaf conversation title after a turn without coupling page routing or persistence to Codex RPC details.
• Isolated title-sync failures so completed responses remain completed.
• Bumped the plugin version to 0.1.1.

Why

Threadleaf conversations were persisted by Codex and appeared in Codex recent tasks, but their user-facing title could fall back to the raw first prompt, including injected page context. Threadleaf already derives a cleaner conversation title, so the provider session should receive the same title.

Impact

New and resumed Threadleaf conversations use the same readable title in Threadleaf and Codex recent tasks. Providers that do not support session titles are unchanged.

Validation

• npm run typecheck
• npm test (43 passing)
• npm run build
• Real Obsidian/Codex app-server verification: the Threadleaf title Reply with exactly SECOND_OK. This intentionally lo… matched the persisted Codex thread title for the same session ID.