[Feature]: Muse effort picker in live-terminal native chat

[clichedmoog]

Problem

#22998 renders Muse transcripts in native chat, but the composer has no session-option pills: the Muse catalog (MUSE_SESSION_OPTION_CATALOG) defines effort only as launch args for supervised workers (#22383). A live terminal session cannot change reasoning effort without typing into the PTY by hand.

(A model picker stays impossible: Muse has no model-listing command, so models: [] by design.)

Proposed scope

• Add midSession: { kind: 'command', build: (value) => '/effort <value>' } to MUSE_EFFORT, reusing the existing 7-level vocabulary and the live-PTY command delivery Claude's /model switch uses.
• Report the current effort for the pill row (the TUI status line already shows model · effort · cwd), mirroring claude-terminal-session-options.
• Stacked on feat(native-chat): render Muse transcripts #22998: the pill only renders inside the Muse chat view that PR adds.

Verification

• Unit tests for catalog dispatch + reported values.
• Manual: dev build, toggle a live Muse session to chat view, pick an effort, confirm the TUI status line changes. Also confirms the /effort <level> slash syntax.

[AmethystLiang]

thanks for the feedback! we're looking into it.