Deactivate streaming copyright pass + smooth reference reveal

[lfnothias]

Summary

Fixes the streaming glitch where the GUI answer froze for ~0.6 s at the body→references boundary (right after the FBMN section) and then dumped the references all at once.

Freeze — deactivate the streaming copyright pass (basic.py)

After the body finished streaming, _apply_copyright_filter ran a synchronous verbatim-detection pass before references were appended — a ~605–668 ms stall. On the streaming (GUI) path this had no user-facing effect: the body had already streamed, and the client ignores the revision event. So the pass is skipped on execute_stream (the non-streaming execute() still runs it for compliance). Also drops the now-unused full_response accumulation.

Dump — smooth the reference reveal (ChatPanel.tsx)

useTypewriter flipped from 12 chars/frame to instant (99999) the moment done arrived, so the one-chunk references block snapped in. It now finishes the buffered tail at a finite 48 chars/frame, easing the references in (~100 ms). Historical loads stay instant — the typewriter starts already caught-up, so no animation runs.

Verification

• Re-ran the FBMN query through the route handler: largest inter-token gap 131 ms (normal jitter), versus the old ~605–668 ms; 0 copyright-detection events on the stream.
• 91 targeted unit tests pass (copyright / basic / stream / reference); frontend compiles clean.

Note: the test CI job fails on the pre-existing test_web_app_routes.py sandbox issue already present on main (passes locally 30/30); unrelated to this change.

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