feat: expose thinkingEffort in the custom status line JSON snapshot

Feature request

Add the current session's effective thinking effort to the JSON snapshot passed on stdin to a custom status line command ([status_line].command in tui.toml).

Current behavior (v0.30.0)

The snapshot contains only:

model, cwd, gitBranch, permissionMode, planMode, contextUsage, contextTokens, maxContextTokens, sessionId, version

The built-in footer renders the model slot as <model> thinking: <effort> from runtime state (state.thinkingEffort), so switching effort at runtime via /model is reflected immediately. A custom status line command cannot reproduce this:

• thinkingEffort is not in the snapshot payload.
• Runtime effort switches are not persisted to config.toml ([thinking].effort stays at its configured default), nor to any session file a script could read.

So with a custom status line configured, the effective effort becomes invisible — a regression versus the built-in layout.

Proposal

Add thinkingEffort (and ideally thinkingEnabled) to the status line payload, sourced from the same runtime state the built-in footer uses. This keeps custom status lines at feature parity with the built-in model slot.

Start at the status line command snapshot generation for [status_line].command and trace the runtime state used by the built-in footer, especially state.thinkingEffort. Verify the stdin JSON reflects runtime changes made through /model, and consider whether thinkingEnabled belongs in the payload as well; done means custom commands can display the effective effort.