Workflow graph visualization in plit-tui

[theuseless-ai]

Goal: Wire the graph-boxes renderer into plit-tui so users can see workflow topology as an ASCII graph alongside the chat interface.

Context: The graph-boxes example in the Tela repo already renders workflow graphs with compact icon nodes, expanded agent nodes with sub-items, branch labels, and loop arrows. This ticket integrates it into the production TUI.

Data flow:

plit api workflow get <slug>
  → API returns nodes + edges
    → Transform to graph-boxes format
      → Render in TUI panel

Features:

• Graph view as a tab/panel in plit-tui (alongside Workflows and Chat)
• j/k navigation between nodes
• HJKL panning for large graphs
• Node selection shows detail in status bar
• Responsive: wide screens show graph + chat side-by-side, narrow shows one at a time
• Live updates via WebSocket when execution is running (nodes light up)

Acceptance Criteria:

• Graph tab/panel added to plit-tui
• Fetches workflow data from API on view open
• Renders compact icon nodes for simple types (trigger, switch, merge, etc.)
• Renders expanded boxes for agent nodes (showing LLM, tools, skills)
• Branch labels on fork bars
• Loop back-arrows rendered correctly
• Keyboard navigation (j/k/H/J/K/L/0)
• Responsive layout (graph + chat on wide, single view on narrow)
• Node selection updates status bar with node detail

Dependencies: DSL parser in Tela/JSX side, graph-boxes design (in progress)

Priority: P1 (transparency layer for conversation-first UX)