Consume odek turn_started frame as primary streaming-card trigger (supersede lazy-open heuristic)

[jkyberneees]

Context

odek PR BackendStack21/odek#180 ships the turn_started wire frame (v1.42.0): emitted for every turn immediately after the session frame and before the first streamed frame.

{ "type": "turn_started", "turn_id": "t_<hex>", "session_id": "…", "initiated": "operator" | "system", "model": "…" }

Streamed frames (thinking / token / tool_call / tool_result / done / error) now carry the same turn_id while the turn is active. Docs: odek docs/WEBUI.md (frame table + compatibility matrix).

Task

Make bodek consume turn_started as the primary trigger for opening the streaming card, superseding the lazy-open heuristic shipped as the client-side mitigation on 2026-09-02.

1. Primary path: open/upsert the streaming card on turn_started, keyed by turn_id. Idempotent: a replayed or duplicate turn_started must never open a second card.
2. Supersede the heuristic: the lazy-open (first inbound stream while idle) drops to belt-and-suspenders — keep it, but it should no longer be load-bearing.
3. Wake turns: rely on initiated: "system" from turn_started instead of the session frame's system_initiated stamp (the stamp remains for old clients but is deprecated as a signal).
4. Reconnect attribution (optional polish): on reconnect mid-turn, use turn_id on streamed frames to attach strays to the existing card instead of guessing from idle state.

Acceptance

• Card opens from turn_started on both operator and system-initiated (wake) turns.
• Duplicate/replayed turn_started is a no-op (upsert by turn_id).
• Lazy-open heuristic retained only as fallback.
• Old-odek compatibility: if the server never sends turn_started, behavior degrades to today's (heuristic path still works).

[jkyberneees]

Closed by #70 (released in v0.21.0).