CLI Polish — the headless CLI becomes a first-class, on-brand surface.

• Styled CLI via charmbracelet/fang. wintui --help, usage, errors, and --version are now rendered to match your active color theme. Shell completions ship via wintui completion <bash|zsh|fish|powershell>, and wintui upgrade --id / wintui show complete package IDs from the local cache (no winget call).
• wintui notes . Fetch and render a package's release notes (markdown, themed) when the winget manifest provides them, with a URL fallback otherwise. wintui check --notes renders the notes for every pending update inline, so you can review what you're about to install before upgrading.
• wintui theme [name] [--list]. Show, list, or set the color theme from the CLI; the active theme also appears in wintui doctor.
• wintui upgrade --self. Upgrade WinTUI itself from the CLI via the startup self-update handoff — the other upgrade modes deliberately skip the running binary, so CLI-only users stay current without launching the TUI.
• wintui list [query]. Filter installed packages by name or id (like winget list); wintui list firefox doubles as an "is it installed?" check (exits 1 when nothing matches).
• Themed CLI output. Release notes match your theme palette; upgrade success/failure markers, per-package headers, and check/list summaries are accent-colored. All color is gated on an interactive terminal and respects NO_COLOR — piped output and --json stay plain.
• Scroll-wheel support in the package list, detail panel, and cleanup tab.

No breaking changes; settings.json is unchanged and cache.json remains backward-compatible (it gains optional truncation metadata).