Fix permission quick input not submitting to executor

[bborn]

Summary

• SendKeyToPane was sending just the key character ("y" or "n") without pressing Enter afterward
• All terminal-based permission prompts require Enter to submit the response — without it, the keystroke sits in the prompt buffer and is never submitted
• Every other send-keys usage in the executor already includes "Enter" (e.g., sending "continue working", "Enter")

Analysis

• The quick y/N input is correctly scoped to permission prompts only (via latestPermissionPrompt() which checks for "Waiting for permission" log entries)
• The tasksNeedingInput map is only populated for permission prompts, not for general MCP taskyou_needs_input questions
• SendKeyToPane is executor-agnostic (sends tmux keystrokes to whatever's running in the pane), and Enter is universally needed for all terminal prompts regardless of executor type (Claude, Codex, Gemini, etc.)

Test plan

• All existing UI tests pass (go test ./internal/ui/)
• All executor tests pass (go test ./internal/executor/)
• Build succeeds (go build ./...)
• Manual: Start a task with Claude executor, wait for permission prompt, press 'y' from kanban — verify it submits
• Manual: Press 'N' from kanban on a permission prompt — verify it denies

🤖 Generated with Claude Code