TUI: Ralph control integration (pause/resume/stop via sentinel files)

[gmickel]

Summary

Integrate Ralph async control commands into flow-next-tui, allowing users to monitor and control Ralph runs from the terminal UI via sentinel files.

Flow Epic: fn-14-wv3

Features

• Display pause/stop state badges in run list
• Show completion_reason for finished runs
• Add keybindings for pause/resume/stop actions (p/r/s)
• Real-time state updates (poll sentinel files)

Motivation

Addresses feedback in #51 - users want to control Ralph runs without leaving the TUI. The sentinel file mechanism from fn-13-pxj is already implemented; this epic exposes those controls in the TUI.

Key Files

• flow-next-tui/src/lib/runs.ts — run discovery, isRunActive()
• flow-next-tui/src/lib/types.ts — type definitions
• Sentinel files: PAUSE, STOP, completion.json in run directories

Related

• Ralph mode inside of Claude code  #51 — user request for interactive TUI controls
• fn-13-pxj — Ralph Async Control (sentinel file infrastructure)

Tasks

• fn-14-wv3.1: Add run control state detection to runs.ts
• fn-14-wv3.2: Show pause/stop badges in run list
• fn-14-wv3.3: Add keybindings for pause/resume/stop
• fn-14-wv3.4: Display completion_reason in run detail