docs: Polish — CLI section separation, card layout, streaming visual

[planetf1]

Context

Several smaller documentation improvements identified during PR #601 review. Grouped here as they are each individually small but benefit from a single pass.

CLI section separation (E9-a)

Comment: m-decompose.md mixes CLI usage with programming model concepts. Consider a dedicated CLI section in the docs nav so users know where to find command-line tools vs Python API guides.

Card layout consistency (C2)

Comment: Landing page (index.mdx) card groups start with 2 columns then switch to 3. Should be consistent throughout for visual polish.

Streaming tutorial visual (C8)

Comment: Tutorial 02 (streaming) would benefit from a visual representation of streaming output — e.g. an animated GIF, a terminal recording, or a diagram showing token-by-token flow.

Files

• docs/docs/guide/m-decompose.md + docs/docs/docs.json (CLI separation)
• docs/docs/index.mdx (card layout)
• docs/docs/tutorials/02-streaming-and-async.md (streaming visual)

Acceptance criteria

• CLI tools have a clear home in the docs nav
• Card columns are consistent on landing page
• Streaming tutorial has a visual aid