UI: 'Germinating...' spinner doesn't clear after background task completion

Description

The "Germinating..." spinner continues to display indefinitely even after a background task has completed successfully. The UI shows "↓ 0 tokens" but doesn't return to the prompt.

Steps to Reproduce

1. Start a Claude Code session
2. Run a background Task agent (e.g., Council or other long-running task)
3. Wait for the background task to complete
4. Observe: "Background command ... completed (exit code 0)" appears
5. But: "Germinating..." spinner continues with "↓ 0 tokens"

Expected Behavior

The spinner should clear and return to the normal prompt state when:

• The background task completes, OR
• No tokens have been received for a reasonable timeout period

Actual Behavior

• Spinner shows "Germinating... (esc to interrupt · Xm Xs · ↓ 0 tokens)"
• User cannot tell if Claude is still processing or stuck
• Must manually press Esc to return to prompt

Screenshot

✻ Germinating… (esc to interrupt · 12m 7s · ↓ 0 tokens)

● Background command "Council: Task Prioritization" completed (exit code 0)

Environment

• Platform: macOS (Darwin 24.6.0)
• Claude Code: Latest version

Impact

• User confusion about session state
• Uncertainty whether to wait or interrupt
• Happens "sehr häufig" (very frequently) according to user report