UI: countdown arc around call button not rendering (visibility/regression)

[rosscado]

Version / Env
v1.10.0 (MVP) • Desktop (Chrome/Firefox/Edge)

Description
The countdown arc that displays the dynamic submit wait time no longer appears. This removes crucial feedback about whether the client is still listening vs. about to submit.

Expected

• Arc renders around the call button during post-speech evaluation; duration scales with computed wait time.
• Arc respects theme modes (light/dark) and any container transforms.

Actual

• Arc is absent across sessions; possibly for several weeks.
• Unsure if style/z-index/masking regression or arc logic is never invoked (e.g., early return path).

Repro

1. Start a call, speak a short utterance, stop talking.
2. Observe call button: no arc animates; submit occurs shortly after.
3. Toggle themes / resize / scroll — still no arc.

Acceptance Criteria

• Arc consistently visible during the wait window on supported browsers.
• Verified contrast in dark mode; not obscured by container overlays (no overflow:hidden clipping or transform stacking issues).
• E2E test asserts presence of arc element and animation during the decision window.

Diagnostics to capture

• DOM snapshot for the call button container; computed styles for arc element (opacity, visibility, display, z-index).
• Check for CSS collisions (e.g., a recent UI wrapper with position:relative; overflow:hidden; clipping the arc).
• Console warnings (e.g., ResizeObserver loop, React hydration mismatch) that could prevent mount.
• Feature flag/prop that enables the arc.

Severity
Medium-High (UX feedback missing; contributes to premature-submit confusion)

Labels
ux ui visual regression

Related to #202